I have been using ELM on the phone for at least a year. Some of my students think it is pretty cool to be able to do their research on their phones. Unfortunately, not a lot of my students actually have smart phones. I work with a total new immigrant population. Still, it is very nice to be able to access ELM and especially Ask a Librarian from the phone.
We also use the St. Paul Public Library app at school a lot. We have 270 Nook HDs and the students use the public library's ebooks. They often use the library app to get to those books and to look up other local library info. The Nooks give my students the chance to use some of these great apps and find good information.