I know it takes a whole 5 minutes and who has 5 minutes, but getting your Akismet API Key and Activating Akismet is well worth your time. I have gotten spam comment after spam comment, even though I have barely updated this blog. So today I did it.
1) Sign-In to your Wordpress.Com account, easy and you should probably already have one.
2) click on this: <a href="https://apikey.wordpress.com/">https://apikey.wordpress.com/</a>
3) copy and paste that key in your Akismet set-up
4) say goodbye to all that frickin' spam.