Notepad.exe
Each session, I copy the contents of last session's character into a new document using the following schema Character Name - Class/Level (Date).txt
I then track HP, GP, equipment, etc in that document. I can literally tell my DM the date, villian, and circumstance under which each piece of treasure was acquired.
I've tried some more advanced solutions, but I find that none of them do everything well. Either the learning curve is too steep, or they don't show enough information, or they're too inflexible to handle our houserules.
Spider