- Manybooks.net - http://manybooks.net One of my favorites for the PC, mainly because it is so easy to drag and drop convert files to make them Kindle ready.
- Calibre ebook management - http://calibre-ebook.com/ Fast becoming my favorite because it works on the Mac as well as the PC. You can edit, convert, organize, and even read your favorite non Amazon books with this.
- Stanza (for your iPhone, as well as PC or Mac) - http://www.lexcycle.com/
- Kindle for PC - http://www.amazon.com/gp/feature.html/ref=kcp_pc_mkt_lnd?docId=1000426311
- Kindle for Mac - http://www.amazon.com/gp/feature.html/ref=kcp_mac_mkt_lnd?docId=1000464931
- Barnes & Noble Reader - http://www.barnesandnoble.com/u/nook-for-pc/379002322/ How bout a taste of that Nook? With this on your iPhone or PC or Mac, you can take advantage of free offerings from Barnes & Noble too.
- iPhone BookShelf - http://www.iphonebookshelf.com/ This has a nifty little server you can install on your mac or pc that allows you to (very easily) transfer your favorite epub files to your iPhone wirelessly. A neat tool to experiment (play) with.
All of these are freeware, no advertising, everything works great, and they all install nice and clean, and won't mess up your computer system. Years ago (Windows XP and before) I would never have installed so many different applications on one machine, but now with Vista and Windows 7, it is much easier. It could be they are just making software better too. Who knows? My Mac has been an experience too, with not much to choose from in the way of software, but what is available is very good, even freeware. Freeware can sometimes mean crapware, but not in the case of anything you will hear about from me.