Infrno is a virtual tabletop and scheduling services (for free!)
Its pretty slick..about to start a game for my brothers who live out of town.
Obsidian Portal is a game management site which many more features (but no virtual tabletop)
I use it to run my local games, it has a built in forum, wiki, campaign log, notes, characters..pretty much anything you need to keep yourself and your players updates/coordinated.
Its not free(but cheap) to own the GM portion, but is free for any of your players to contribute and view all your content.
Unfortunately these are two separate sites at the moment.
I have spoken to the developer of Obsidian Portal and he said he is working with the Infrno team to possible link their two services, but he told me they will probable remain separate.
Tis a shame because both do their "thing" very well, but it would be nice to have them on a single site
Edit: Here is a link to our Shadowrun game...its has made all of our lives much much easier
http://www.obsidianportal.com/campaigns/gurps-sr