Keeping track of all the email you have to answer can be tough, and Gmail's starring system makes it a bit easier. Starred is a Mac app that sits up in your menu bar and simply displays only your starred Gmail messages. This may seem a little dull, but it can actually help you turn your inbox into a to-do list.
I have a pretty full inbox and it can be tough getting through all of it. I fail more days than I succeed, in fact, but starred messages help me keep track of what I really need to reply to most urgently. Starred is a really handy app for me because it essentially creates a to-do list that's automatically populated and conveniently located in my menu bar. This makes remembering to access these messages really handy. You can even preview the entire message just by selecting it. Personally, I'd prefer to be able to open it in my mail client, and I assume others would prefer an option to open in Gmail as well, but since most of my emails involve a task rather than just responding it makes for a really useful list of reminders. The one thing that would be really great is if it could handle multiple accounts. Still, a nice free utility to help keep your day on track.
Starred [Mac App Store]