Ghostscript should work, see
http://stackoverflow.com/questions/1...th-ghostscript /
http://www.cs.virginia.edu/~weimer/pdfsplit/pdfsplit for examples.
Anyhow I didn't split PDF files for a long time, currently I prefer creating huge PDF files from multiple sources. Searching in one file is usually more convenient for offline clients.
PS:
http://pages.uoregon.edu/koch/ has a Mac pkg - I don't have a Mac so I won't test it.