Are there any repositories around for open sourced iPhone components?

For instance, I have found myself needing to create several new types of table cells to mimic some of Apple's existing functionality (for instance, all the different types of table cells present in the Settings application). I can't imagine I'm alone here.

Where do you go to find open sourced reusable components, or do you just write and hoard your own?

Update: I know there are open source full projects around (see this question), but rummaging through them and picking and choosing still leads to significant duplication of effort.

Update 2: Here are some libraries that I've found (or have come into existence) since asking this question:

• Three20 -- Custom UI classes used in the Facebook application
• CocoaHelpers -- Extensions to common classes
• MBProgressHUD -- Replacement for the undocumented UIProgressHUD