Here is a selection of links, that should give you an idea of places to go, when you need to start programing in Tcl, learning more about the commands provided by eggdrop/Tcl and more advanced areas.
One of the better things you can do, is to have a overall goal. once you have this, look at scripts, that do similar tasks to what you may do, or involve tasks that yours will. You can get a feel for how yours will operate from this.
http://dmoz.org/C.../IRC/Bots/Eggdrop/* - Selection of sites, related to eggdrop and Tcl scripts.
http://www.tcl.tk/man/... - Tcl manual pages. Lists all the commands available in Tcl, as a core default.
http://suninet.the-demon.de/ - One of the best guides to coding in Tcl, and heavily focused on using it in eggdrop.
If you are looking for some advanced functions, including FTP access, e-mail send and receive, and some other advanced statistical and storage functions, these links may help.
http://tcllib.sourceforge.net/ - TclLIB homepage. Provides a selection of packages, designed for some advanced programming needs.
For newsgroup (USENET) help, you can take a look at alt.irc.bots.eggdrop(google viewer).
There are some other Tcl archives and so on in the Links section of Egghelp.org, and lists of IRC Channels that may be able to help you.
If you wish to add one to the list, simply make a reply, and I will accommodate it.
* I am affiliated with this Dmoz.org category.
Post updated today July 20, 2010.