I am now writing up my doctoral thesis. It is in theoretical physics so not very challenging as for language but still I would like to have corrected some parts like dedication, acknowledgement and the introduction by a native speaker. (Especially the dedication part needs some hints, as I wanted to be very original in it so I have to be sure that it sounds as I wanted it to sound:-) I know there are sites (though I forgot what) where people help each other on a reciprocal basis. Recommendations?
Note: I am not sure what tags this question should have, feel free to add some.