You're still here? Okay, another way is spreading the word about how much you love their books. Put a review on Goodreads or LibraryThing. But since you have crafted your review so lovingly, why not put it in other places too, such as Amazon.com and Amazon.co.uk (I only recently discovered that you can copy your same review and put it on different Amazon sites). And add the your review to your blog if you have one. You wrote those words, be proud of them and your lovingly crafted intelligent review!
The thing is, unless an author is a golden egg for a major publisher they might not get much promotion done for them. If they're self-published, they won't get any promotion done for them! And believe me, getting word out is both expensive and time-consuming for the author. So their main avenue for discovery is good reviews, in as many places as possible. If you put your review in multiple places you not only get best use out of the time you spent writing the review, and help potential purchasers on other sites, but you help the author along, help to spread the word - and authors are grateful for that. Getting your name known for achieving something in your craft is the only way to take things further, and that's an area where the reader and the author depend on each other.
So, next time you find that a writer succeeded in creating a world and a story that filled your waking moments, shout it out from the hilltops. Karma may come your way!