Rather than a hybrid system, in my current campaign, we used an either/or system. Originally we rolled up using a set of home rules based off the 4-14 scale used in Alternity, although we later converted to 3e.
At any rate, in 3e terms, it would've been something like this:
Player chooses point selection or dice rolling. Once made, there is no going back.
Player chooses point selection (one for one from total available pool, not scaled like point buy). It would take some work to figure out what the total would be like on a 3-18 scale, but it was roughly a few points lower than the average total you would end up with choosing option 2 below. Basically this was a safety choice. You could always get a decently workable character without worrying about bad rolls.
Or player chooses to roll, allowing for the possibility of an exceptional or below average character. Player rolls two sets of six scores (4d6, drop lowest). No mixing between the two sets is allowed. Then the player chooses which set to keep and assignes to the six abilities as desired.
No matter which method I use, I always stipulate that the final results are subject to DM's approval.
Eight players rolled up characters, and every one of them chose to roll. Most of the characters ended up with point totals slightly above what they would have had with point selection. One player ended up with a two low scores (5 and 6 I believe). He wanted to play a dwarven figher anyway and didn't mind having low Int & Wis since he had good rolls for his physical abilities and decent charisma.
Kenjib, I'm intrigued by your system but I think it would need more testing. I have found that it takes many, many sample rolls to really get a good sense of how a system works out.
Psion, I agree with you that the S&P system was easy to abuse. However, the problem was not simply point buy, the main problem was the subability scores. It was too easy to pump one subability and leave the other hanging. Some examples:
If you didn't plan on focusing on missile weapons, it was a no brainer to pump up the defensive side (balance?) of Dex and leave yourself with a low Aim.
Likewise, almost everyone would pump up the side of Str that affected your damage adjustment and be content with a lower carrying capacity.