It used to frustrate me to no end that I couldn’t sort my Gmail inbox by Attachments like you can in Outlook, bringing all the messages with attachments to the top. Being able to do that is particularly important when you start to approach the 7GB limit and you need to clear out some old garbage.
So when I realized how to see just messages with attachments it was like a light went off in my head. Know you search operators!
To see messages with attachments search for has:attachment. You can search for specific file types like this: filename:pdf. That will give you a list of all the messages with pdfs attached.
There are a bunch of other operators such as in (in:inbox, in:trash, in:spam), is (is:starred, is:unread, is:read), and date operators (after:2004/04/16, before:2004/04/18).
See the complete list in Gmail Help.