Anyone that reads on a mobile device, but doesn't dig Amazon's Kindle thing is probably using Aldiko. This is a super-popular ebook reader that supports EPUB, PDF, and Adobe DRM ebooks. It also works with titles rented through public libraries. You're probably going to wish it worked with more services because the new update looks excellent.
If you're getting tired of reading eBooks on a tiny phone screen or looking for a new eReader application for that shiny new tablet, check out Aldiko Book Reader. This popular eBook application just received a huge update geared toward tablet users. It has an entirely new tablet-optimized user interface, which means reading books on your device will look much better than before. In addition to the user interface overhaul, here's everything else the update includes: