If you're not watching Veronica Mars on UPN, you're missing one of the best shows on TV right now. It's one of the few shows that advances a continuous mythology and story arc while still doing one-off plots contained to an episode. It's very well written and clever without being predictable or annoying. Sure, we've heard of "Who killed Lilly Kane" before, but even this far in the season, I can't say whodunnit.
There's also the issue that Kristen Bell, the star of the show, is absolutely adorable. She's so cute I could squeeze her. (If I keep referring to young hot girls like this, she's 24, they're going to reject my application for the Dirty Old Man club.) She manages to be the superhero/fallen popular high school girl we all want to cheer for, but still pulls off the vulnerable type when it counts. She's supported by a pretty good cast all around, including Enrico Colantoni as her dad.