The following links will take you away from this website. They provide what I consider to be useful tools in the ongoing fight against malicious software.
I will disclose the fact that I am a former malware researcher for Malwarebytes. I will refrain from comment regarding any programs I list here, as I believe they are all very useful in the war against malware. They are listed in random order. If your program isn't on here, it's probably because I've just missed it. I know of many programs which can be helpful, I will get the best ones listed here with a link soon enough. Thanks!

MalwareBytes.org Creators of MalWareBytes AntiMalware (MBAM)
Trend Micro's Hijackthis
SuperAntispyware An excellent program that does a very nice job of cleaning up most messes you could encounter
Max's malware removal pages