
Update 3/19/2013
You can now actually run a search for attachments based on size! Approved operators:
- size:5m – Find emails with attachments of 5M
- larger:5m – Find e-mails with attachments larger than 5M
Suggested query: larger:5m older_than:2y
^ Will find all e-mails larger than 5MB and older than 2 years.

Gmail inbox getting full? Mine was too. For some inexplicable reason, Google does not allow you to run a simple search of your inbox where you can sort by attachment size. There are some options to get your Gmail account under control, most useful of which is searching for particular file types. Run a search for the most commonly large file types, and optionally add a date modifier so you only look at mail older than a certain date.
Enter this into the search box:
filename:(mpg OR mpeg OR avi OR wmv OR zip OR bmp OR mp3 OR wma OR mov) before:2010/12/31
Note: Change the “before” date to whatever date you want. It can even be today’s date.
I did not exclude JPG or JPEG because pictures are often a useful thing to save. I still recommend going through each e-mail before doing a mass-delete with the above search query, but this will at least give you a useful workaround while Google works on a sortable attachment filter.
Google is well aware of the need for this feature, but feel free to cast your vote on their suggestion page, like I did.

Make sure to vote for Google to add this as an official function.