Windows/Mac/Linux: UltraCopier is a cross-platform file copier with an emphasis on enhancing native OS file transfer with error checking, transfer pause/resume and speed control.
For many copy handlers the emphasis is on raw speed — something that, historically, many OS file copiers were poor at. UltraCopier is plenty speedy when you run it wide open, but it also includes a speed regulator for those times you don't want to saturate your network or choke a drive during extended file transfers. Another handy feature UltraCopier sports is search within the copy list. If you've ever set up a bulk copy before and then wondered if a key file was somewhere in the massive queue, you'll appreciate the ease of search UltraCopier brings to bulk file transfer.
UltraCopier is free and available for Windows, Mac OS X and Linux. For more file-copying options, check out the Hive Five on best alternative file copiers.