[I thought this worth repeating in its own thread]
Don't forget with the browser you can download books from mobileread.com and feedbooks.com. Just put the download guides on them. Type these URLs in your Kindles browser to get them:
https://www.mobileread.com/mobiguide
http://www.feedbooks.com/kindleguide
Once those "books" are on your Kindle you can browse/search through them and d/l books directly to your Kindle... free of charge.
These are public domain and creative commons books that are perfectly legal and legit and can be shared with all your friends too.
BOb