I recently set up a dual-boot box with Red Hat 7.0 and FreeBSD 4.2. 
Earlier today, I attempted to make it a triple-boot box by installing
Wolverine which is the most recent beta for Red Hat's upcoming
release.  I had been using the FreeBSD boot manager, BootEasy, but the
documentation for BootEasy is almost non-existent and I couldn't
figure out how to make BootEasy boot Wolverine in addition to the two
already established operating systems.  (It could be that the boot
partition was an extended partition beyond the magic 8Gig limit.)

Anyway, I went out searching for a new boot manager and found two of
them.  The one that I haven't tried (yet, anyway) is GRUB:

    http://www.gnu.org/software/grub/grub.html

It is part of the GNU project and is GPL'd.  There's been no official
release yet, though development versions are available.

The one that I did install is GAG.  See

    http://raster.cibermillennium.com/gageng.htm

It's a graphical boot manager and was super easy to install and
configure.  It is able to boot the three OSes that I have installed on
the box and apparently is capable of booting up to six more.  It is
also licensed under the GPL.  The only (minor) complaint that I have
about it is that the documentation was written by someone whose native
tongue is definitely not English.  Still, it was comprehensible, and I
had no problem getting the program to work.

Kevin