sansa e260R and a mac

Is there anyway to add mp3s to the sansa e260R from a mac computer?

Sure . . . as long as they are .mp3 format and not the proprietary Apple format ( .aac or .mp4). Set your player to MSC / Rhapsody mode in Settings > USB Mode and connect to your Mac. Then just drag & drop from the computer to the Music folder on your player.