Bog plants...do you want emergent or submersed species? If you have the space emergent plants can look really nice and will help push the bog effect. Pond supply places will have plenty of suitable species come spring time.
Are you going for a biotope? If so, where?
*EDIT* I found your picture thread, scratch the emergent plant suggestion. Many disturbed ponds that I have seen have lots of floating plants- duckweed, water meal (it's the devil, don't get it), maybe azolla, and a few stem plants like hornwort (looks like you've already got it), ludwigia, or najas (readily available from any aquarium supplier). Of course, if you really want the funky look you'll need mats of floating macroalgae like Ulothrix or Hydrodictyon.