Tenkar asked about alignment.
Pretty much, Alignment didn't matter much in my games. It mattered more in my High School Unearthed Arcana days, since we had a Paladin and a Ranger/Druid in the party, so the most evil person in the group was Lawful Neutral. People chose it, and it "mattered," but I don't recall it being a big deal. The players were on one side, the bad guys on the other, and you fought. No evil PCs, no backstabbing party members, no worrying that the LG guy and the N guy were together for 32 adventures in a row and pretty much acted the same way, which was they killed monsters and tried to complete the module and level up.
Believe it or not, I used Alignment in my first, 1e GURPS games. We had a full (well, too full) collection of disadvantages and people chose their Alignment, too.
It mattered here and there, for magic weapons with alignment. But in general, it was there because the setting (the Forgotten Realms) and my players expected it. We had lots of "Chaotic Evil" comments to work out of our system. I don't recall it coming up that much overall, and later copies of the PCs lack an alignment at all, which means it was mostly cosmetic adaptation to the game system that underpinned the world we chose to play in.
Once that was done, my next group - not that many years later - was pure GURPS. No alignment. Evil is what evil does, Good is what good does. Only supernatural creatures got the truly Good or Evil designations, and they mostly didn't matter in play since there wasn't a lot of magic or whatever that affected you based on that designation.
Looking at it now, I can see it be useful in either a Law vs. Chaos game, or a Good vs. Evil game (they're similar but not the same.) It seems like it started as a simple, "What side are you on, if any?" and grew into a complex system of action-restriction descriptions coupled with languages and game effects from spells. I don't think a nine point system with everyone taking one is really that useful. It ends up being potential proscriptive, not descriptive, and a weight on actions. Disadvantages might seem the same way, but they tend to drive a lot of interesting play rather than restrict actions per se. They limit by opportunity costs (the Overconfident guy loses out on the chance to run away, the Greedy guy goes for the money and misses the moral reward elsewhere, the guy with Sense of Duty chooses potential death over leaving a man behind) rather than by "Alignment X wouldn't act that way." Which, sadly, is how I remember Alignment mattering when it mattered at all.
Is it needed? No. Useful in selection situations? Yes. You could do the same thing without the tags, though, given a system that supports it. Or bolt-on support in a system that uses Alignment.