Screenshot capturing software

Any recommendations on a decent screenshot capturing software? Think of taking screenshots within HL2DM, push the key as many times as you want, as quickly as you want and it automatically takes a screenshot and saves it to the screenshot folder. I would like to be able to do that exact same thing but with whatever is being displayed on my screen at the time at any time (not within HL2DM).

Fraps does this right? (Also video capturing software as well…)
http://www.fraps.com/

Thanks for the response, I’ve been using Debut. It’s free for consumer use but you have to pay for commercial use but it does exactly what I need it to.