The built in screenshot shortcuts work just fine. If you're looking for something a little more robust with annotation tools, checkout Little Snapper: http://www.realmacsoftware.com/littlesnapper/

SnapNDrag. Looks like they've got an app in the mac app store now, but they also still have a free downloadable dmg, and it's totally worth taking a look.

BTW, did you mean "Rediscover the joy..." It says "Rediscovery the joy..."

command + shift + 4 (+ spacebar to capture only the window)

This looks good (I can't download at work due to the proxy, but will later), thanks