Two indispensable and free screenshot tools are Jing and BugShooter. Jing uploads your screenshot to the web and copies the link to it to your clipboard so you can just share a URL in your DoneDone issue. Bugshooter integrates with DoneDone, so all you do is point, shoot, and tell it which issue to upload it to.
No more saving to your desktop, or using photoshop, or plopping into powerpoint. Bam.