@ lambots:
You may want to check out the website Epic Words. It's a campaign management program that is similar to Obsidian Portal, but it was developed before Obsidian Portal. Anyway, it's a pretty cool program that offers a limited free account. However, the last time I checked it was like $12 USD to subscribe for a year of service.
Anyway, each campaign created there has it's own forum, wiki, journal feature, and a wealth of other campaign tracking features. It also has an automatic (i.e., reoccurring) game session notification feature.
Under a free account, a GM can create one active Campaign, and a player can have up to three active characters, IIRC. Anyway, the point being that if you are only going to use it for one Campaign, then both you (the GM) and your players only need to subscribe for the free account option.
However, the really cool thing about the free account is that you can archive your characters or campaigns. For example, as a GM you can archive your free campaign, and this frees up your slot so that you can create another active campaign. It works the same way for active characters as well; i.e., you can archive a character to free up one of three active slots allowed in the free account.
Epic Words: <a href="http://www.epicwords.com/" rel="nofollow">http://www.epicwords.com/</a>
This may be the droid you are looking for! :D
Cheers,
Michael