The Google Search box in Gmail Labs makes it easy to quickly search and paste results into an email without ever clicking away. If you don't like sidebar clutter, a button on your email toolbar now offers the same search-and-paste convenience.
If you use a script or add-on that hides your Gmail sidebar boxes, or you'd rather keep the Google Search toolbar minimised, you can now activate the bottom-right search box pop-in with the "G" button on your email composition toolbar. Hit it, search for what you need, then hit the arrow icon when you hover over a result to grab the full result text or just the URL link and paste it into your email.
Small convenience, sure, but perfect for when you're just looking to pass on a helpful link or recommendation.