With the recent establishment of the ability to lend ebooks with the Kindle and the Nook, several 'swap clubs' have sprung up around the net where you can make your ebooks available for lending and borrow ebooks from others. I've tried three of the services and have found that they all work, although the last one I've tried has been FAR more successful.
Booklending.com (formly Kindlelending.com until Amazon complained about their trademark). This is a pretty good service. It operations on a 'push' principle. When you log in you register what books you are interested in, and then wait for someone to send them to you. When you make your books available it will show if anyone is waiting for those books and offer up to 3 people that you can send to.
It has a limited ability to see which books are available for lending, but no real strong search capabilities. I've received several books from here and it works OK.
I've also lent books from this site. When you lend a book it opens Amazon in a frame and you can then use the Amazon lending capabilities to send your book out. When you list the books you have available you have to manually enter them.
http://www.lendink.com/ Lendink is another site, it has an advantage in that you can see what books are available and search by genre. It operates on a 'pull' principle. When you see a book you are interested in you can click it and the site will send an email to the owner of the book that you are interested in lending it.
I've also lent books through this service. It operates very similarly to the booklending.com site. When you list the books you have available you have to manually enter them.
This site supports both Nook and kindle books.
Finally the last and best site is:
This is the latest site I've tried. Unlike the other sites you have to enter your books before you can borrow from it. It provides a bookmark that runs a script on your Amazon page to parse out which books you have available. It then saves all of those and figures out which ones are lendable.
It gives you two credits (loans) to start, and then as you register books it gives you more. I had 10 credits after I parsed out my books.
For the previous sites you want to request many books, you don't have a good hit ratio. However for lendle.me I had a 7 out of 10 books lent to me in less than 48 hours, I had requested several because based on the other sites I expected to only get 2-3 hits with 10 requests. Lendle.me seems to have a wider selection of books (probably because it parses them from Amazon). I can generally read a book in 2 days, so I'm going to have to stop requesting just to keep up.
If you are borrowing Kindle books, I recommend lendle.me, if you are borrowing Nook books then lendink is your choice. However it doesn't hurt to be on all 3 sites to maximize your borrowing and lending chances.
I've been using the lending services to borrow books that I would check out of a library. I've added some new authors to my 'buy list' after doing so. It stretches my dollars and makes me more likely to take a chance, you can borrow the first book in a series and see if you want to be spending your money on the rest.