Seems like I say this every thread these days:
I use DMGenie. Even when I'm a player.
It lets me track pretty much every aspect of my character and I just print out a fresh sheet every level. I don't mind it looking like crap, I even crib my XP in the margins with calculations and everything. It looks a little rough, but when the next level rolls around I have a fresh sheet.
My last GM used DMGenie (Alot of us liked it) and it was nice to have him be able to check the sheet and let me know what was what, and when we leveled up I could send him an export of the PC and he'd upload it and have it ready to rock and roll.
A trick I picked up BEFORE I used software ... for all the erase-prone parts of the sheet ... cover those areas in mid/non-glossy clear tape. You can still write on it with a #2 pencil, but it doesn't wear out when you erase it. You have to rub pretty hard with your finger to wipe it off, but it's not as permanent as writing on the paper itself. Worked well for me, anyway.
Now, though, with DMGenie, when I run games I keep the PCs for my players and print them out a new sheet each level. Everybody seemed to really like that. Nobody was SOL if they forgot or misplaced their character sheet, the sheets were always clean looking, stuff was well laid out and easy to find, etc.
--fje