Thought it was worth mentioning because so many people have been wanting to send e-mail attachments of any type. By default, Android only allows you to send pictures as attachments. Gravel Mail seems to do one thing and one thing only: sends e-mail attachments to people you want using your own SMTP account. Just search for Gravel Mail. My only criticism of this application is that it's not a full SMTP client. It only sends e-mails. I think with some work it could be though!