I have some large files that I need to change the compression type of for input to a program--I need to unrar them and then gzip (or bzip2) them.  However, they're highly compressed files and I don't have the disk space to unrar them fully then gzip them.  Is there any way to pipe the output of decompression via unrar to gzip or some other compression without saving the entire intermediate result to disk?
Changing compression in memory
command line;pipe;compression;rar