Today, Google added a new auto-complete feature to Gmail Labs. Once enabled, Google says, "with this new Labs feature you can just type a couple letters and select the desired contact from the drop down list. Easy and quick as that."
In addition to auto-complete, Google has added more power to its search operators to make search more efficient.
It explains, "You can search in specific places (e.g., in chats or sent items), or search for messages with attachments of a certain type (e.g. docs or photos)." On top of that, it will let you add specific types of attachments or file formats when you need to find a specific email with a certain attachment.
I enabled the Search Auto-Complete Lab to test it out, and it crashed Firefox on me. I re-loaded and attempted to perform a search to see how it would work, and it crashed again. I disabled the Lab in response.
Perhaps it's not quite ready, or my Firefox is being cranky today. Either is possible.
Still, check it out for yourself.