Gmail Labs: Get experimental features in Gmail

Tonight, Google has released a bunch of new experimental features in Gmail, which you can enable any of them through a “Labs” tab in your setting area. Interesting enough - this is a development effort of Google developers’ free 20% time. Initially, there are 13 features available:

Most of them could enhance your productivity (except the Old Snakey game). I have enabled three most useful features:

1. Quick Links. Consider this feature as your shortcut to any pages in Gmail. You could save your frequently used search queries for quick access. I would say this is the navigation interface in Gmail now. Very handy.
2. Superstars. I usually star a message when it “needs reply”, or “read later”. This is a souped up version of the Star feature in Gmail. Now you can identify different types of important message, say using “exclamation mark” for “need reply”, and “blue star” for “need to read”.
3. Fixed width font. This feature is so useful, as some emails may contain space formatted, ASCII art or table which requires fixed width font to display probably. Change to fixed width through the reply dropdown menu when you see a misaligned email.

Which experimental features do you use?