Sources

CodeSourcery, LLC
CodeSourcery, LLC: CodeSourcery, LLC. Development tools, especially for C and C++. The premiere provider of support, enhancement, and extension services for the GNU Compiler Collection (gcc) and the GNU development toolchain (binutils, gdb).
http://www.codesourcery.com/

Hsoi's Shop
source code: Hsoi's App Shell, WASTE Object Handlers; PowerPlant Classes: CURLPushButton, CVersCaption, HCmdButtonAttachment, HMarqueeCaption, HSharableResource, HSharablePicture, HStringList, HToggleRadioButton
http://www.hsoi.com/hsoishop/

iDevGames.com
Features source code for Mac games and encourages submissions.
http://www.idevgames.com/

Ingemar's Corner
Archive of source-code, all commented, mostly in Pascal. Also home of SAT (Sprite Animation Toolkit).
http://pascal-central.com/ingemars-corner.html

SourceForge
Source code repository
http://sourceforge.net/