finder
OS X´s finder can mount NFS-exports only if they don´t use an reserved socket port number (<1024), but Debian-boxes‘ nfsd-service uses these numbers by default. For exporting using unreseved ports, use insecure-key in /etc/exports on the Debian-box, eg:
/data *(rw,no_root_squash,insecure)
Now one can use Connect to Server oder AppleKey-K and as address nfs://servername/export for mounting.
mount_nfs
In terminal: mount_nfs -P servername:/export /mnt
Using automount
For using automount one has to do some NetInfo-settings. These can be easily done by NFS Manager or manualy using NetInfo-Manager oder nicl (in terminal). The entries are shown in the last posting
Sources:
http://www.fifi.org/cgi-bin/man2html/usr/share/man/man5/exports.5.gz
http://www.withay.com/macosx/nfs-client.html