Here's another thing I like.
The 3.0 edition finally solved the problem for me of introducing snakes and spiders into the game-- I mean, NORMAL snakes and spiders. Back in the old 1e days, there weren't, as far as I know, any "official" normal vipers or tarantuals. Just the giant kind. Which is sort of lame, because the real creatures are great opponents. Or at least good for a scare.
So, 3.0 put them into the game. Bravo. Finally.
But 3.5 has done them one better. 3.5 has introduced-- SWARMS!!! Yes, for the first time as far as I know, there's a consistent mechanic for dealing with swarms of hungry (normal) rats and swarms of flying (normal) bats and even swarms of normal centipedes and spiders and locusts too!
That's been something I've always wanted a mechanic for, because I just love the atmosphere of these things. Everytime Indiana Jones faced a swarm of bugs or rats, I wished the game would finally introduce a workable mechanic for handling them. Well, finally, they have.