ust-virtual-server-mobile - The Mobile devices theme for Usermin. You want it if you ever use your mobile device to read mail or whatever via Usermin.
ust-virtualmin-nuvola - Deprecated. You don't want it. Ignore it. I'll get rid of it.
wbm-virtualmin-google-analytics - Support for automatically adding analytics JavaScript bugs to web pages. If you have mod_perl 2 installed and enabled, this makes it easy to insure you have those bugs on all pages, without having to edit templates and HTML files directly. It's required for the Piwik analytics Install Script, as well, since it uses a JavaScript bug like Google Analytics and others.
wbm-virtualmin-notes - Administrator note pad. It's just a text area for making notes to yourself or other administrative level users. Doesn't really do much, but a couple of folks asked for it and it was easy to build.
wbm-virtualmin-oracle - Create databases in an Oracle database. Same as with MySQL or PostgreSQL. Note that it does not provide any UI for tables and such (like MySQL or PostgreSQL). It just creates and manages the databases and users via Virtualmin.
wbm-virtualmin-password-recovery - Allow passwords to be mailed to a user that has forgotten it. Kind of iffy, but folks wanted it, so we made it.
wbm-virtualmin-signup - Allow anonymous users to create mailboxes for themselves.
Very iffy. But some folks wanted it for intranets and such. I'd suggest being very careful with this one. The only protection against spammers abusing your system is a CAPTCHA.
wbm-virtualmin-slavedns - If you have an existing DNS server that cannot be brought under control of Virtualmin or Webmin, you can have Virtualmin automatically become a slave to it for all new zones using this module. Most folks don't need it. But, if you're a big hosting provider and want all DNS consolidated on a pair of master servers, this is the module for you. (And, it's easy to add a post-create command to have the zone created by Virtualmin.)
wbm-virtualmin-sqlite - Just another database, as with the Oracle module.
wbm-virtualmin-support - This one was announced and thoroughly described here:
http://www.virtualmin.com/forums/news/virtualmin-support-module.html#17232 
