What the title says. Basically, any books you think need more recognition or just aren't popular enough. This means that they have a small fanbase, but deserve more, or isn't appreciated enough.

For me, I'd say The Inheritance Cycle by Christopher Paolini is underrated. Sure, it's known around the readers circle of people, but it's way better than some claim. Even though a few parts aren't executed that greatly, I really loved a few storylines and the entire story feels very nostalgic to me.

I'd also add obscure science fiction stories from the seventies of which I find musty copies of anthologies in my library. Lem and Asimov are some of the greats here, but there are so many more random short stories I have never heard anyone talk of that deserve it.

Lastly, even though it's also not entirely unheard of, the Ranger's Apprentice series by John Flanagan is absolutely awesome. I love every single one of the characters to the Moon and back and the plot is always fun. The general atmosphere of being a Ranger -- running around in the forest, shooting with a bow and arrow, being masters of invisibility and drinking your coffee with honey -- is something I can just think about for ever without getting tired of.

Anyways, those were my thoughts! I'd love to hear what you lot have to say, and, until then, have a good day!