I agree with Susan, you don't really need specal harp notation unless you mean for specific harp effects like glissando etc. Any piano music is fairly close. If you know how to do chords on the harp then any guitar music will work as well, but the important thing is to find music without lots of accidentals if you don't have a pedal harp - you spend more time flipping levers than playing the actual music.I have a lot of the books from Sylvia Woods and many of them are songs with accompaniment. She has a website with an on-line catalogue.
http://www.harpcenter.com/Merchant/index.html
Also there is the harp e-mail mailing list - the easiest way to subscribe is to go to:
http://www.onelist.com/subscribe/harplist
Helen