Yeah, I have.

The two file transfer clients I've tried are AndFTP and DroidFTP. I deleted AndFTP, but don't take that as much praise for DroidFTP. Regular FTP connects, but simply doesn't work with all FTP servers. SFTP (that is, ssh's file transfer protocol) seems to work fine. The user interface is … marginal. AndFTP also supports FTPS (that is, Regular FTP tunneled via SSL/TLS) but also fails on some FTP servers, and it supports ssh key authentication, but only DSA keys, for some reason. I don't remember why I liked DroidFTP better; the UI was probably less irritating.

SwiFTP is actually an FTP server, but is what I used to transfer several GB of data off of a microSD card I didn't have any other adapter for. I was surprised to note that it barely used any battery during the few hours of transferring.