Software for copying large amounts of data?

I often use the Terminal for large copies (particularly for large numbers of files, as opposed to just large file). It doesn't crap out when there's a problem, just continues past it, and I can hide it and go back to it without affecting the operation of the rest of the computer significantly.

cp -Rvn

I use that all the time (remove the n if you want it to overwrite files in the destination).

jW

Unless you're moving data from machine to machine and particularly want a GUI-based FTP app, absolutely no software is needed or generally used for what you describe. Copy & move operations are fundamental to any OS and available as a basic tool, both in the UI and at the command line.