Calibre Portable helps organize and keep track of your e-books. You can read e-books though the app as well.
Sync and conversion: Through Calibre Portable, you can sync all of your e-books, so no matter where you want to read them, you'll always pick them up in just the right place. You can also convert e-books from one format to another to make them compatible with various e-book readers and other mobile devices. Output format options include MOBI, EPUB, AZW3, FB2, HTMLZ, LIT, PDB, PDF, and more.
Customizing the look: There are also quite a few options available for customizing the appearance of the pages including the table of contents, the page setup, and the look and feel of the pages themselves.
Search: You can also search for new books directly through the app. When you use this feature, you'll be presented with many options for each listing, so you can quickly find the best deal on the book you want to read next.
Freezing: This app did freeze and crash a couple of times during testing. It did always open back up again without issues, however.
Calibre Portable is a great option whether you have an extensive e-book library already or are just getting started. It provides clear options for syncing and converting e-books, as well as keeping them centrally located, so you can find what you're looking for quickly.