Hoople - 7:09 pm on Jun 14, 2011 (gmt 0)
I would add a few high quality directory links from the many that are available.
A few (<3) links in niche / industry specific directories. With the number of links you presently have I wouldn't go beyond that. I would space these link placements out over time to not trip a non natural linking penalty. DMOZ and BOTW are also options but likely will not drive any visitors.
A few (<3) links in directories having a large ammount of links in your niche's area.
A few (<3) links in a regional directories in the sub category matching the site's chosen location. (Country - State - city/county).
Your existing links are all top notch - adding some more 'pedestrian' quality links (but still valuable - not spam) will hopefully get G to give your site some link love in the SERPS.