It all depends on what you're going to do with it...
For example, SecondMonitorHorizSync is of absolutely no use whatsoever, to me, but that's because I don't use TwinView. Since you (I guess) do, you might find it useful.
NvAgp is also of no use to me, since the default setting (try agpgart, and if that doesn't work, try nvidia-internal AGP) works fine for my chipset. Those using nForce chipsets, though, need to set NvAgp to 1 so that agpgart isn't used.
There are scenarios for just about all the options, where some would find them absolutely essential, and others don't need to even use them.
Best advice -- figure out what you want to do (sounds like you already have that one down though), and just read through all the options in the README file, Appendix D. Check out Appendix M, as well, on UBB, page flipping, and whatnot. If you see something that looks cool, try it out. Make sure you keep a backup of your config file, though, so if it screws something up, you can revert to the backup.