Gmail Labs is the playarea for Gmail folks to release new features and check their usage among the public. If this is something new to you, check out this post on Introduction to Gmail Labs.
Did you get an invoice or a report in the mail body and wish to save it in a document? Forget about copying the content and look no further than the “Create Document” Labs feature. Once you have enabled Labs as discussed in the introduction post, navigate to Settings -> Labs and choose to enable the “Create Document”:
Once this is enabled, whenever you get a mail, following can be noticed on right top corner.
Click on the “Create a Document” link and a nicely formatted document from the mail gets created and saved into your Google Docs area. Simple isn’t it! Try it out and let me know.