For me, one of the most useful tools of Gmail is the drafts feature, and it just got better with text formatting. If you purchase something online and they expect you to keep the information on that page as a receipt, start a new blank message in Gmail, select the entire web page you want to save and paste it into Gmail and save it as a draft. It will save the page including formatting.

wow thats pretty scary i just did that about an hour ago. i was on the laptop and i got a "please print this for your records" and i go "oh cool it will save all my formatting and the images if i put it in google" but i guess you beat me to the idea (your post was five hours before my revelation)