Given the release of the new Kindles, I figured I'd talk about another aspect of ebooks. That is, doing a better job of getting the books you want onto your reader.
Swiss Army Knife
All of the ebook readers I've played with have had absolutely abysmal tools for searching and sorting your books. They're gradually getting better, but still fall down a lot when you have hundreds of books. Luckily, there's a swiss army knife for ebooks. It's called Calibre.
Calibre will import most any ebook format and can interface with pretty much all the different readers out there. It does a great job converting and transferring files to and from both Kindle and iTunes. You'll want to check out Apprentice Alf for some plugins that will remove the DRM from your ebooks so you can freely swap them back and forth between devices. This will also let you share books with your SO even if you have separate Amazon accounts.
Calibre will let you tag, rate and sort your ebooks pretty much however you'd like. I even go so far as to have separate libraries for fiction and non-fiction (things like ratings just don't translate well between the two). When books are first imported, they come in without any ratings. I let this be my flag for "haven't read this one yet" and make sure to rate them once I've either read the book or decided that it sucks and I won't finish it.
If you're like me, inconsistencies in your collection will drive you nuts. You can use Calibre to correct author names (sometimes they show up as Stross, Charles instead of Charles Stross) and cover art. Alternatively, you can strip out cover art all together if you really want to save space on your device. You can also group your books by series and specify an order for them, so you won't keep having to go back to Jim Butcher's website to figure out what book comes next while you re-read the series.
Calibre has an ebook search feature that does double duty as a comparison shopping tool. Amazon pretty much always wins on price, but sometimes you'll find books that aren't available from Amazon (like most books from Baen).
Another tool in the cheap books utility belt is the kindle best seller list. Notice that it's got separate lists for free and paid. Amazon breaks their best seller list down into genres and sub-genres, so you can get pretty specific. This is usually done as a loss leader to get you interested in an author, so don't expect all their other books to be free. At least there's no monetary risk for trying out a new author this way.
Another cool tool for saving money on books is eReaderIQ. eReaderIQ mainly highlights books that have had their price drop, but you can also search Amazon by price (something not available in the normal Amazon UI). You can say "I want a sci-fi novel that costs $5 or less". Lots of indie publishers and self-published authors have begun publishing at $1, $3 and $5 price points. Don't let the low prices scare you away. There's some really good fiction at those prices.
In theory, ebooks are supposed to come out with a high price while the book is in hardcover, then get cheaper as paperbacks are released. eReaderIQ's Kindle Price Drop will notify you if an ebook's price drops by a specified amount, so you know when that drop happens.
Don't hold your breath waiting for it, though. In eight months I've only seen the price drop on 2 out of a bit more than a dozen books. One of those (Neal Stephenson's Reamde) has gone down, but not hit my alert limit. The Complaints by Ian Rankin actually dropped enough to hit my limit and I was duly notified. The system works - publishers just don't drop prices very quickly. That's why you so often see kindle versions priced higher than paperbacks.
I still use Kindle Price Drop, because it makes a great "to be read when the price is lower" list. I just keep adding books to it when they're released and then looking over my list when I'm hunting for something to read. Maybe the price will be lower, maybe not. Most importantly, I won't forget to check the price on something when I'm waiting for it to come out on paperback.
Finally, there are the Kindle Owner's Lending Library and a program whereby you can check out kindle books from your local library. I haven't played with either of those yet, though the selection on the Kindle Owner's Lending Library seemed rather scant.