if you don't qualify for Adsense or simply don't like it, you may consider Abdrite or Bidvertiser ... or if you are from the USA, try Yahoo YPN. Anyway, Adsense plays best for content rich pages. You may also try Infolinks, upon me, it is the best in-text advertising network.
Yahoo is not as good as Adsense. However CPA ads may yield you much more if they are placed strategically.
If you are from the USA you can use ads from Microsoft or Yahoo,if not, try Bidvertiser or some other PPC networks!