Chrome: While it's easy to organise your Gmail inbox with stars and the trusted trio of labels, sometimes it's still hard to tell why a message was important. Chrome extension Gmail Notes annotates messages and sync your notes with Google Docs.
Sure if you just need to remember to look at a message or reply to the sender, stars and labels are more than enough to remind you. But sometimes, if you have a rather long or important message that you need to attend to later, you might want to jot down a few notes as to why that message is important or what you need to do to follow up.
Gmail Notes only shows itself in your address bar when you're viewing a conversation in Gmail, so it stays out of the way when you're browsing elsewhere. Clicking on it will create a new note in a popup, which you can edit, save and access later on just by returning to that conversation. You can also view all your notes in Google Docs from any computer or browser, even if it doesn't have Gmail Notes installed. If you're regularly swamped with email, it's a good way to spend less time asking "Why did I star this?" and more time getting things done.
Gmail Notes is a free download, works wherever Chrome does.