Earlier I posted on how to download torrents via Firefox. But the real old-school chatters and downloaders, they use IRC --which is less likely to be blocked at your college campus.

ChatZilla provides all the usual IRC client features: multiple servers, a built-in list of standard networks, easy searching and sorting of available channels, logging, and DCC chat and file transfers, plus easy customization with JavaScript plug-ins and CSS styling.

To search for downloads, check out:
IRC Klipper - ircklipper.info/search.php
Packetnews - packetnews.com
MyDownloader - mydownloader.com
IRCDig - ircdig.com
XDCCz - xdccz.com

Now, ChatZilla will automatically recognize the links to join a particular server, but if you also want it to recognize the XDCC commands, you'll have to do this:

1. Type about:config in the Firefox address bar.
2. Type signed.applets.codebase_principal_support in the filter.
3. Double-click to change its value to True.

Then, with IRC Klipper at least, click the Pack link, and you should be good to go.