Google offers a potpourri of source code snippets from their varying Mac projects qua Google Objective-C Toolbox.
The Box contains Mac and iPhone compatible sources and offers several additions to Foundation and Appkit as well as new classes to aid in integrating Google services. In brief:

- Geometry libraries to manipulate NSRect, NSPoint, and similar.
- Additions to NSBezierPath, including GCPath conversions, round rects, and shading
- gzip for NSData
- HTTP Server
- HTTP URL Fetcher
- Regex Library
and much much more.

Especially the regex library is just what I need. There are several other external regex libraries for Cocoa, but just recently I tried to use one of those and they were either outdated, not maintained anymore, didn’t compile or lacked certain features. I didn’t try to Google library yet, but I’m hoping for a good solution. This comes in very handy, especially for iPhone.
You can find the library here.