Here's a method to take the edge off of the imbalances of rolling and also avoid the repetitive and predictable stat allocations of point buy.
Organic Point Buy Ability Score Generation Method
Created by myself with modifications from nsruf
1. Roll 3d6 for each stat in order and take all scores where they fall.
2. Swap a single pair of ability scores.
3. Calculate your point total as if you had created this character with the standard point buy rules.
4. Consult your DM regarding the baseline for the campaign (25 point, 28 point, 32 point, etc.).*
5. If your character as rolled has a total point value greater than the baseline amount, congratulations! You get 4 additional points to spend at will as per the point buy rules.
6. If your character as rolled has a point total less than the baseline amount, subtract your total from the baseline. You may spend the greater of 4 or this value at will as per the point buy rules.
* When determining this baseline, DM's should consider that it is quite possible for a character to end up with a character 4 or more points higher than this value. This is not a hard upper limit as it is under standard point buy rules, nor is it a minimum.
score - point cost
8 (or less) - 0*
9 - 1
10 - 2
11 - 3
12 - 4
13 - 5
14 - 6
15 - 8
16 - 10
17 - 13
18 - 16
* It costs 1 point per ability point to raise an ability score below 8
--------EXAMPLE 1--------
For all of these examples I'm coming up with character concept before rolling, and using a 25 point base.
I'm going to make a scholarly archeologist/spellunker/explorer archetype rogue/fighter character. Here's what I rolled up (str, dex, con, int, wis, cha in order):
Roll 1: 1, 5, 3 = 9.
Roll 2: 4, 2, 3 = 9.
Roll 3: 5, 4, 5 = 14.
Roll 4: 4, 2, 4 = 10.
Roll 5: 2, 4, 6 = 12.
Roll 6: 2, 2, 1 = 5.
Pretty craptastic! Well at least let me switch wis and dex. Now I have:
str: 9
dex: 12
con: 14
int: 10
wis: 9
cha: 5
This is a 14 pt. character. 25-14 = 11, which is much larger than 4, so I get 11 additional points to spend. Let's spend those points to raise str to 10, int to 14, and dex to 16. Now I have completed stats at:
str: 10
dex: 16
con: 14
int: 14
wis: 9
cha: 5
I think this guy has spent far too much time with his books, rather than people. His unrelenting drive toward adventurous pursuits has left him somewhat lacking in social skills...
--------EXAMPLE 2--------
A travelling monk:
Roll 1: 3, 1, 6 = 10.
Roll 2: 5, 2, 6 = 13.
Roll 3: 2, 4, 3 = 9.
Roll 4: 3, 6, 5 = 14.
Roll 5: 2, 2, 6 = 10.
Roll 6: 4, 2, 1 = 7.
switch int and wis for:
str: 10
dex: 13
con: 9
int: 10
wis: 14
cha: 7
16 point character gives me 9 points left. I end up with:
str: 14
dex: 14
con: 12
int: 10
wis: 14
cha: 8
--------EXAMPLE 3--------
A ranger rolls:
Roll 1: 1, 3, 3 = 7.
Roll 2: 6, 1, 6 = 13.
Roll 3: 4, 2, 5 = 11.
Roll 4: 6, 6, 4 = 16.
Roll 5: 3, 5, 6 = 14.
Roll 6: 4, 2, 6 = 12.
This is a pretty lucky roll for straight 3d6. I'm switching int with strength for:
str: 16
dex: 13
con: 11
int: 7
wis: 14
cha: 12
This is a 28 point character, which is greater than the 25 point limit. So I get 4 points to spend, which is the minimum (you always get at least 4 points to spend). So, I end up with:
str: 16
dex: 14
con: 12
int: 9
wis: 14
cha: 12
This rather lucky rolls still pays off, but the deviance is not as drastic as straight rolling might be. First, 4 of his points are buried in the cha stat (which he probably wouldn't have done by choice), second the spread between various important stats may not be exactly as he would have chosen (he might have wanter higher dex, for example, along with a lower wisdom because he knows that he could always boost it up by the time he needs it later), and third the first two examples got extra points to make sure they at least reached a threshold of competence.
----------------
If these example stat sets are ending up too low (or disparate) on average for your taste, just up the point buy threshhold to 28 or 32. The higher the point buy value, the more customization is also available post-roll, since you end up with more points to spend on average.
Organic Point Buy Ability Score Generation Method
Created by myself with modifications from nsruf
1. Roll 3d6 for each stat in order and take all scores where they fall.
2. Swap a single pair of ability scores.
3. Calculate your point total as if you had created this character with the standard point buy rules.
4. Consult your DM regarding the baseline for the campaign (25 point, 28 point, 32 point, etc.).*
5. If your character as rolled has a total point value greater than the baseline amount, congratulations! You get 4 additional points to spend at will as per the point buy rules.
6. If your character as rolled has a point total less than the baseline amount, subtract your total from the baseline. You may spend the greater of 4 or this value at will as per the point buy rules.
* When determining this baseline, DM's should consider that it is quite possible for a character to end up with a character 4 or more points higher than this value. This is not a hard upper limit as it is under standard point buy rules, nor is it a minimum.
score - point cost
8 (or less) - 0*
9 - 1
10 - 2
11 - 3
12 - 4
13 - 5
14 - 6
15 - 8
16 - 10
17 - 13
18 - 16
* It costs 1 point per ability point to raise an ability score below 8
--------EXAMPLE 1--------
For all of these examples I'm coming up with character concept before rolling, and using a 25 point base.
I'm going to make a scholarly archeologist/spellunker/explorer archetype rogue/fighter character. Here's what I rolled up (str, dex, con, int, wis, cha in order):
Roll 1: 1, 5, 3 = 9.
Roll 2: 4, 2, 3 = 9.
Roll 3: 5, 4, 5 = 14.
Roll 4: 4, 2, 4 = 10.
Roll 5: 2, 4, 6 = 12.
Roll 6: 2, 2, 1 = 5.
Pretty craptastic! Well at least let me switch wis and dex. Now I have:
str: 9
dex: 12
con: 14
int: 10
wis: 9
cha: 5
This is a 14 pt. character. 25-14 = 11, which is much larger than 4, so I get 11 additional points to spend. Let's spend those points to raise str to 10, int to 14, and dex to 16. Now I have completed stats at:
str: 10
dex: 16
con: 14
int: 14
wis: 9
cha: 5
I think this guy has spent far too much time with his books, rather than people. His unrelenting drive toward adventurous pursuits has left him somewhat lacking in social skills...

--------EXAMPLE 2--------
A travelling monk:
Roll 1: 3, 1, 6 = 10.
Roll 2: 5, 2, 6 = 13.
Roll 3: 2, 4, 3 = 9.
Roll 4: 3, 6, 5 = 14.
Roll 5: 2, 2, 6 = 10.
Roll 6: 4, 2, 1 = 7.
switch int and wis for:
str: 10
dex: 13
con: 9
int: 10
wis: 14
cha: 7
16 point character gives me 9 points left. I end up with:
str: 14
dex: 14
con: 12
int: 10
wis: 14
cha: 8
--------EXAMPLE 3--------
A ranger rolls:
Roll 1: 1, 3, 3 = 7.
Roll 2: 6, 1, 6 = 13.
Roll 3: 4, 2, 5 = 11.
Roll 4: 6, 6, 4 = 16.
Roll 5: 3, 5, 6 = 14.
Roll 6: 4, 2, 6 = 12.
This is a pretty lucky roll for straight 3d6. I'm switching int with strength for:
str: 16
dex: 13
con: 11
int: 7
wis: 14
cha: 12
This is a 28 point character, which is greater than the 25 point limit. So I get 4 points to spend, which is the minimum (you always get at least 4 points to spend). So, I end up with:
str: 16
dex: 14
con: 12
int: 9
wis: 14
cha: 12
This rather lucky rolls still pays off, but the deviance is not as drastic as straight rolling might be. First, 4 of his points are buried in the cha stat (which he probably wouldn't have done by choice), second the spread between various important stats may not be exactly as he would have chosen (he might have wanter higher dex, for example, along with a lower wisdom because he knows that he could always boost it up by the time he needs it later), and third the first two examples got extra points to make sure they at least reached a threshold of competence.
----------------
If these example stat sets are ending up too low (or disparate) on average for your taste, just up the point buy threshhold to 28 or 32. The higher the point buy value, the more customization is also available post-roll, since you end up with more points to spend on average.