Here are some methods I came up with before I posted this thread that had been stewing in the back of my mind for a few weeks.
Method One:
Step 1: Choose a race and assign racial modifiers to appropriate abilities. Elf for example: +2 Dex, -2 Con All standard character generation so far.
Step 2: Choose a class. A class will also give ability modifiers as listed below. Wizard give the character a +2 Int, and a +1 Dex The idea is that a character would go into a field where he has talent and interest and further developed those abilities during their apprentice training. This is along the same thought line as why/how characters get an ability score boost at upper levels in the core rules. These modifiers are only received by starting characters at creation. Multiclassing later give no further ability enhancements.
Step 3: Roll the 3d6 and assign to the abilities in the order they are rolled. I tried this a few times last night and it seemed to work well. You may want to limit any particular score to 18 but I do not think that is necessary. With the distribution of the rolls, inability to assign the rolls to a particular ability, and other racial modifiers you may end up in a rare instance with a half-orc with 22 strength but other abilities like intelligence (-2) and charisma (-2) with very low single digit scores. That could be interesting roleplaying.
Step two gives the characters 3 points they can assign to any ability score. At the DMs option, they can be assigned as the character chooses to a prime, secondary, and perhaps even tertiary ability. No more than +2 should be assigned to any one ability. The default assignments of the 3 points are as follows. This was easy to determine for the "core" classes but a little harder to determine for the classes like druid, ranger, paladin, etc. but here is a shot:
Barbarian: +2 Con, +1 Str, or perhaps +1 Str, +1 Con, and +1 Wis (since lots of their base skills use Wisdom)
Bards: I dislike bards. I just do not see singing during a battle. I am also not a fan of musicals. ;o)
Cleric: +2 Wis, +1 Int
Druid: +2 Wis, +1 Cha (since their animal empathy skills use Charisma)
Figher: +2 Str, +1 Dex or perhaps +1 Str, Dex, and Con
Monk: +2 Wis, +1 Dex or perhaps +1 Wis, Str, and Dex
Paladin: +1 Wis, Str, and Cha
Rogue: +2 Dex, +1 Int
Sorcerer: +2 Cha, +1 Int or perhaps +1 Cha, Int, and Dex or Con. Hmmm, a hard one.
Wizard: +2 Int, +1 Dex
I think that is all of the classes.
Method 2:
Another option that uses part of above but gives very different results works like this. Tally up all modifiers for an ability. You will always roll at least three dice for an ability. Add the sum of the mofidiers to the 3 dice. Our half orc fighter for example has +2 Str Racial and +2 Str Fighter for a total of +4. So roll 7d6 (4 for the modifiers and 3 for normal rolls). Out of the 7 dice, sum up the three highest. This keeps the 18 limit and also tends to get a high score for the character's main attribute ability score.
Now for the half orc's Intelligence (-2 Racial Modifier). Roll 5d6 (2 + 3). BUT now, take the sum of the three lowest rolls.
Here is a quick reference chart for how this works:
Sum of.....Roll this....Sum up
Modifiers...of D6s.....these dice
------------------------------------
+4...........7............3 highest
+3...........6............3 highest
+2...........5............3 highest
+1...........4............3 highest
0.............3............take results
-1...........4............3 lowest
-2...........5............3 lowest
-3...........6............3 lowest
-4...........7............3 lowest*
*(still possible to have an 18 but very unlikely since you would have to roll 7 6s)
Method 3:
And a third variation would be:
Sum of.......Roll this....Sum up
Modifiers....# of D6s...these dice
------------------------------------
+4..........3...............Reroll all 1s, 2s, 3s, and 4s (min score of 15)
+3..........3...............Reroll all 1s, 2s, and 3s (min score of 12)
+2..........3...............Reroll all 1s, and 2s (min score of 9)
+1..........3...............Reroll all 1s (min core of 6)
0............3...............take results
-1...........3...............Reroll all 6s, (max score of 15)
-2...........3...............Reroll all 5s and 6s, (max score of 12)
-3...........3...............Reroll all 4s, 5s, and 6s (max score of 9)
-4...........3...............Reroll all 3s, 4s, 5s, and 6s (max score of 6)
This scheme may be a little too limiting but I like the first two schemes (especially Method 2) and a version of what someone else mentioned...
Method 4:
Player chooses one prime ability for the character. Roll 5d6 drop 2.
Player chooses two secondary abilities. Roll 4d6 drop 1.
Roll remaining abilities 3d6.
Apply racial modifiers.
