Lets share some links....

Right off the presses

GMP / MPFR / MPC for 68020-60 target. Just extract this files into / on a native system. Built specifically to build a native version of GCC 4.5.0
GMP 4.3.2
MPFR 2.4.2
MPC 0.8.1

Here is some stuff I have built. Just the highlights. You can see everything @ http://www.radix.net/~atari/mint/

Native GCC 4.4.3 for the 68000. Works great.
http://www.radix.net/~atari/mint/new/gcc-4.4.3-1.m68kmint.rpm
http://www.radix.net/~atari/mint/new/gcc-c++-4.4.3-1.m68kmint.rpm

GCC 4.4.3 binaries only compiled for 68020-60. Seem to work fine. I have not done any testing to see if they work better than there 68000 counterparts. Just extract this archive over the existing install from /
http://www.radix.net/~atari/mint/new/gcc-4.4.3-020-binaries.tar.bz2

GCC 4.4.3 binaries only compiled for Coldfire. Totally untested! Just extract this archive over the existing install from /
http://www.radix.net/~atari/mint/new/gcc-4.4.3-v4e-binaries.tar.bz2

OpenSSL 0.9.8l with binaries built for 68000, but libraries built for 68000 / 68020-60 / Coldfire. Coldfire has not been tested. I am currently working on build OpenSSL 1.0.0.
http://www.radix.net/~atari/mint/new/openssl-0.9.8l-2.m68kmint.rpm
http://www.radix.net/~atari/mint/new/openssl-0.9.8l-2.src.rpm
http://www.radix.net/~atari/mint/new/openssl-devel-0.9.8l-2.m68kmint.rpm

Zlib 1.2.3 built just like the above OpenSSL, includes the libraries for all 3 targets.
http://www.radix.net/~atari/mint/new/zlib-1.2.3-1.m68kmint.rpm
http://www.radix.net/~atari/mint/new/zlib-1.2.3-1.src.rpm
http://www.radix.net/~atari/mint/new/zlib-devel-1.2.3-1.m68kmint.rpm

For the brave, http://www.radix.net/~atari/mint/new/ includes some binaries targeted for 68020-60 (Like OpenSSH) that are RPMs, and also has modified rpmrc files to support these. I don't support this, yet, as this is something that needs to be decided on as a group, basically the direction to head as far as how to support multiple targets.

Here is an older revision of LibGMP built for the 68000, and fully tested. Newer revisions for the 68000 have issues.
http://www.radix.net/~atari/mint/gmp-4.2.4-1.m68kmint.rpm
http://www.radix.net/~atari/mint/gmp-4.2.4-1.src.rpm

Lzip
http://www.radix.net/~atari/mint/lzip-1.5-1.m68kmint.rpm
http://www.radix.net/~atari/mint/lzip-1.5-1.src.rpm

Lzo
http://www.radix.net/~atari/mint/lzo-2.03-1.m68kmint.rpm
http://www.radix.net/~atari/mint/lzo-2.03-1.src.rpm

A working version of the MPC lib for 68000, compiled against the older revision of GMP
http://www.radix.net/~atari/mint/mpc-0.8.1-atari.tar.bz2

Subversion, which seems to work well, used heavily in ScummVM development. Many of the prereqs for building it are also present in the same directory.
http://www.radix.net/~atari/mint/subversion-1.5.6-1.m68kmint.rpm
http://www.radix.net/~atari/mint/subversion-1.5.6-1.src.rpm