I find that organizing all the data I have on my characters, locations, etc really help me when working on a book. It can be hard sometimes to keep everything straight. “What was so-and-so’s uncle’s name?” and “Errr what colour were his eyes again?” can be easily answered with a character sheet much like you might have for a roleplaying character.
Unlike a roleplaying character, though novel characters tend to need some different categories for info. For example: They don’t need hit points and they probably don’t need a list of what’s in their inventory, but they do need a good list of hobbies and a description of what their home looks like.
I browsed online to see what templates were out there for novel characters and simply couldn’t find anything that suited me. So, I made my own. I will share it here, filled out with the stats for an as-yet unused character concept I had just so you can see how I make use of the fields. Feel free to download it and use it, add to it. Whatever you like. I hope it serves you well.
Edit: Since Google Docs seems to like to muck with my picture-placement for no discernable reason, here is the same document in .odt for those of you who use Open Office.