5: ASAP Utilities
This Excel add-in is probably one of the most popular -- and it has endured. ASAP Utilities is the turn-to application for both frequent and infrequent users, but for different reasons. For the frequent user, it provides an easy-to-use interface that's just more efficient than Excel. Infrequent users will rely on that interface because solutions are easier to find and implement. If you ever find yourself thinking, I know Excel can do this, but how?, turn to ASAP Utilities.
Susan Sales Harkins is an IT consultant, specializing in desktop solutions. Previously, she was editor in chief for The Cobb Group, the world's largest publisher of technical journals.