I have found the HathiTrust site valuable in my dissertation research, as it has a good number of out of print books in my field which Duke doesn't carry. I think it is also an advantage because I have found that many of these books from the period 1875-1925 are in poor condition, and I would prefer to use a digital copy rather than risk further damage to the volume itself. I also encourage Duke to partner more with HathiTrust--some items seem to only be searchable with a logon from a partner institution. Duke is not currently in their list, but luckily my undergrad logon still works for library access :) I would have to say though, it is rather infuriating to see something listed in the catalog that I don't have access to. It's a tantalizing carrot dangling in front of me, out of reach--and I love carrots.