There are a plethora of great file compression tools for OS X, including the built-in Archive Utility. These programs take one or more files or folders and compress them into a single (or segmented) archive that can more easily be transfered and expanded later. Many people will be familiar with the concept of a "Zip" file, which seems to be the lingua franca of the file compression world. But it doesn't always provide the needed functionality.
Most of the available apps will do the job, but if you're giving the compressed files to others you need to make sure they can easily decompress them. You may also be concerned about the time it takes to compress the source files and folders. Additionally, breaking the resulting compressed file into pieces may be needed for more easily recovered downloads via FTP, for e-mail transfer, etc.
The tool that I found, which provides the answer to these needs, is BetterZip (http://macitbetter.com or in the Mac App Store). It's a commercial app, but at the time of this writing its cost is only $19.95 USD. If you use file compression often, it's well worth the cost.
So, assuming you're with me on the recommendation to purchase BetterZip, I'll break down its optimal usage for various scenarios below.
Cross-platform sharing with a single archive
Use ZIP format. The decompression support is built into both Windows and OS X.
Cross-platform sharing with a multi-file archive
Use 7Zip format. On Windows the 7Zip program is a free download (http://www.7-zip.org). BetterZip handles it on OS X.
OS X with a single or multi-file archive
Use TAR format with BZIP2 compression. The decompression support is built into OS X. And when compressing the file(s) it uses multiple cpu cores for lightning fast compression times. In fact, I just compressed a 9 GB file while writing this post. It finished before me.
If you want to use the lightning-quick compression of TAR with BZIP2 compression, but need to break the archive into multiple files, simply compress it as a single file, then re-compress it using 7Zip format, which supports segmentation. In order to do this, you must open BetterZip and create a new archive. Then, instead of dragging the large compressed archive into the new window, use the File menu's "Add to Archive" command. Otherwise, BetterZip will think that you want to merely open the file you're dragging into the window. When saving, be sure to turn down the compression setting to "no compression", so that it breaks the file up without trying to re-compress it.