I’ve played around with a few ereading apps while trying to find the perfect one for proofing books. While I test all my formatted files on an actual Kindle and an actual Nook, sometimes I need to check quick things by computer.
These are the ones I use:
The Kindle app for mobi files – free and easy to download.
If you don’t use Firefox (why on earth are you still using Internet Explorer??), the second best would be the Nook app. The old version doesn’t allow you to DELETE the files you add, which is a pain in the A**. If they’ve fixed that since I last downloaded it – bravo. Then it doesn’t suck too badly anymore. It displays images much larger than any other epub reader, so keep that in mind.