How To Easily Find Large Attachments in Gmail, without 3rd Party Tools

Thanks to steabert on stackexchange for posting this helpful tip!

In Gmail, simply search for “size:xxxxxxxx

This undocumented search parameter will help you find messages larger than the size you searched for.
The search parameters are in bytes, so 10485760 = 10MB or  52428800 = 50 MB, and so on.

EDIT: As of November 15th, Google has officially released support for this feature

“To find emails larger than 5MB, you can search for size:5m or larger:5m