[CyberMonkey]

Oh there are TONS of stuff here.
As far as ROMs go, it depends on who you talk to that will tell you which ones they like. Best I can say is try a few and go with the one you like best.
As far as other customizations, there are threads that deal with just about every aspect; if you use S2U2 there's a thread on customizing that, HTC Home Customizer, even the startup animation and splash screen.....