If you're doing a good job at work, keep a record. Office productivity site Slacker Manager suggests keeping a "yay-me!" file:
The basic idea is simple: you just keep a file of good stuff you do. When you figure out some trick new process that saves hours per week, you make a note about (don't forget to datestamp it) and drop it in the yay-me file.
There are two benefits of this practice: first, you can always give yourself a pat on the back when you're feeling down. Second, you're storing up good karma for your annual (or otherwise) evaluation. Do you have a "yay-me" file? Share how you've used it in the comments.