Here's how to mount unix file systems onto your OS X Mac. I haven't done nfs exports from the mac to other unix systems, but the link at the bottom for the command-line method should let you figure it out.
For a similar discussion, including more methods, see this HOWTO. Also, this discussion for command-line method.
First, you need to have the administrator of the unix system give your machine permission to mount volumes on that system. You will have very disappointing results otherwise. Also, if you did not set your uid number to that on the unix system (see previous step), you will not have owner privileges for your files on the mounted volume.
For a temporary mount for light-duty work where a stable connection is not needed, you can follow the instructions in AppleCare Document 25344
the Finder uses an unprivileged port to do this, which may not work with some NFS server configurations. Also, is not automatic on rebooting, so you need to re-mount when you reboot.
This sets up a standard unix nfs mount, which is presumably what you want if you are reading this. Note that you most likely need to run the Repair Privileges utility first.
Property Value(s) vfstype nfs dir /tao name tao:/home/tao/salathe opts (-b, -P, -s)
% sudo -s % ps -aux | grep -E "nfsiod|automount" root 241 0.0 0.0 1276 84 ?? S 0:00.03 nfsiod -n 4 root 242 0.0 0.0 1276 84 ?? S 0:00.00 nfsiod -n 4 root 243 0.0 0.0 1276 84 ?? S 0:00.00 nfsiod -n 4 root 244 0.0 0.0 1276 84 ?? S 0:00.00 nfsiod -n 4 root 251 0.0 0.1 2392 440 ?? Ss 0:00.08 automount -m /Netwo root 413 0.0 0.0 1112 196 std R+ 0:00.00 grep -E nfsiod|auto % kill -HUP 241 242 243 244 251 [or whatever the pids]
Note: Sometimes when the computer goes to sleep and wakes up, mounted volumes are not fully accessible from Finder. They are still there at command line. To fix this, use the "force quit" feature to restart Finder.
You can also do this on the command line.
There is also a shareware gui, NFSManager. I think you need to pay the $17 before it will work.