I'm a longtime fan of CopyPaste, but here's a freeware program that does something similar -- store clips for later use. The clips are available from the menu bar and paste into the frontmost application.
MacJournal is a great way to file away snippets of information or organize or thoughts. You could even use it as a journal, and publish your thoughts to a blog. This program recently went commercial, but there is still a freeware version available -- it's just not being developed any more.
Keep track of contacts, appointments, to-do lists and memos in a single, integrated application. It synchronizes with a Palm handheld, but you can use it without.
Pastor is a password-protected spot to stash serial numbers, passwords and the like. Once I got started, I was amazed at how many I had. Now they're all in one, easy-to-find place instead of all over the place.
Here's an amazing little program that allows you to organize all those miscellaneous notes that don't seem to have anywhere else to go. Sidenote has lots of features and a spiffy interface.