I did a private message giving Gadget my linked list unit and instructions on using it. I still fancy adding a bit more functionality to it before posting a link here, though. In the meantime, I'll point people in the direction of other Delphi container classes.

Julian Bucknall (author of "Tomes of Delphi") has some container classes here:
http://www.boyet.com/FixedArticles/EZDSL.html

Also, there's a project at SourceForge called Decal:
http://sourceforge.net/projects/decal/