I recently downloaded ISC's DHCP daemon for use with my Mac, and was a little perturbed that it didn't compile to a universal binary by default. Fortunately, it's fairly easy to do so.

Once you've downloaded it, and expanded to a top-level directory, type:

apple$ ./configure --disable-dependency-tracking
apple$ export CFLAGS=-arch i386 -arch x86_64 -arch ppc -arch ppc64
apple$ make

If you don't configure with the --disable-dependency-tracking flag, you're apt to get an error message like:

gcc-4.0: -E, -S, -save-temps and -M options are not allowed with multiple -arch flags

Note that this trick isn't specific to DHCPD; other configure-based tools that exhibit the same error message can probably be solved in the same manner.