I am using the screenshot app that comes with elementary. Love it for its simplicity and works a treat, but I feel its missing a feature.
Namely, I would like the ability to take a screenshot based on user entered pixel dimensions.
Quite often when developing websites you may wish to have pictures of a specific dimension, usually to cut down on page load speed and avoid generating unnecessary overhead. For instance I have a need at the moment for a bunch of images at 750px x 400px. Now I can take a screenshot at 1920 x 1080 and go into gimp and edit it down but its an extra step that adds time...
Just one for the suggestion box ;)