Forum not listed in a Google search

Our forum wordnerds.omgforum.net is a fansite dedicated to David Cook and his fans. It has been active for more than four years now and it still isn't showing in Google searches for key words like david cook, david cook fansite, cook forum, etc. etc.

Do you know how can we make it to appear?

It is listed:
http://www.google.com/#q=david+cook+fansite&hl=en&prmd=imvnso&ei=r5y5T6XyEfDEsQKDmZyLDA&start=10&sa=N&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=d8a6b950f5a13cbe&biw=1366&bih=600
The fifth entry.

Hi,

For me it even comes up as the THIRD result, congratulations on such a successful forum
=> http://www.google.co.uk/#hl=en&sclient=psy-ab&q=David+cook+fan+forum&oq=David+cook+fan+forum&aq=f&aqi=g-K1&aql=1&gs_l=hp.3..0i30.13369.17652.2.17930.12.11.1.0.0.0.125.1121.6j5.11.0.eish.1.0.0.zCZkHIt7nP8&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=4d2a2500bec4723&biw=1366&bih=664