I just bought this game on sale on Steam, figured it should have matured more by now.
My favourite mods so far:
No bloom, but keeps HDR.
No DOF effect when driving fast.
Reduced AI agression to 55%, this one lets you actually RACE without it turning into bumper cars like the game is set by default on higher levels.
The tyre mod, that adds multiple slip angle etc.
I haven't tried the F1 2009 mod yet, their basically almost direct ports from rfactor etc.
After you play with the game for a while, it really is quite good game with excellent graphics. 1920x1200 4x(AA) 16x(AF) max settings and bloom off with vsync, is really really pretty.

Edit: forgot to add, there is a mod that fixes also all the FFB and wheel issues with G25 etc.

Leave it up to community to fix that one, eh?