Super excited to read both of these! Dark Inside sounds like an amazing post-apocalyptic read. From its description, it sounds like it has four main characters that share the spotlight, which is interesting in itself. Being a paleo nerd, I'm super geeked about Rex Riders. My reaction when I saw the cover on LibraryThing was pure, unadulterated, excited nerdiness.
Waterfall by Lisa T. Bergren (Free ebook)
I've heard amazing things about both of these time-travelling themed books. I would probably still have wanted to read them anyway even if it weren't for the positive buzz because I love time travel! Perhaps I'll read them one after another to compare them. Thanks to Elodie for hosting the Ruby Red giveaway and Small Review for letting me know about the free Waterfall ebook!