For a long time, you could only get an Akismet API key by creating a wordpress.com account. From what it seems though, that’s no longer the case. It seems that Akismet.com is offering personal keys directly on their site, http://akismet.com/personal.

What is Akismet? Akismet is an anti-spam protection plugin. It will let you protect yourself against spam. It does an incredible good job of moving spam comments into the spam folder. It saves a lot of time because you don’t have to filter through all the comments that come through and wonder if they are spam or not.

It’s not 100% fool proof, some manual spam still gets through, but it does an amazing job and I activate it on all blogs I ever install.