If you liked the Clocktaur Wars books then you may like Swordheart, which is in the same world a few years later. No crossover characters, though, and I am giving a seriously skeptical look at the author's tastes in romance. Still, it's very enjoyable. (You know, of course, that she also writes middle grade under the name Ursula Vernon, right? I'm convinced that her MG books are a work of genius, wonderful for capable but reluctant readers. Summer in Orcus is terrific.)