mtdev

Using nfs exports on OS X is pretty easy, it's core is FreeBSD based after all. To mount an nfs share go to Applications - Utilities - NetInfo Manager. Select mounts, then from the Directory menu (that's on top of the screen), select New subdirectory. From the same menu select New property a few times. You'll have to edit the names and values to get something like this:

type = nfs
dir = /Users/martin/foo
opts = -P
name = 10.0.0.1:/bar

/Users/martin/foo might not be the best place to mount it, maybe some OS X guru knows better, but I'm new to OS X. As with other Unices make sure the directory exists in advance.

The -P switch is needed to send nfs client requests from ports < 1024, that's usually required by nfs servers. It might work for you without that switch but if it doesn't try with it first before trying anything else to troubleshoot it.

name is the hostname or ip address of the nfs server, and /bar is the export name.

You have to click somewhere else before proceeding to save your changes, I was getting used to the aplly changes immediately thing in OS X but it doesn't work here.

After you've saved the changes you have to signal the automount daemon so it reloads its config, you do that with sudo kill -HUP `cat /var/run/automount.pid`.

Your nfs export should be mounted now and ready to use.