I'd also consider a grade skip or at least requesting a meeting with the GT coordinator for the district to do an Iowa Acceleration Scale on her to see if she'd be a good candidate for a skip or subject acceleration.
My oldest's best year in language arts pre-skipping was 3rd and that was b/c she was placed in an accelerated 4th grade language arts class for that part of the day with a really, really good teacher. She got to skip out on all of the drill of third grade LA: cursive practice, reading logs, grammar, etc. and instead focus on learning how to do research reports and develop presentations on the material she had researched, read unabridged classics, and generally just learn something.
FWIW, I don't consider my dd a prodigy either but she's done really well with grade acceleration, subject acceleration, and more atypical interventions that not everyone in GT/enrichment programming considers.
In regard to good 4th grade level books, these aren't necessarily funny, but my dd loved the old Choose Your Own Adventure books when she was reading at about that level. I know that they've reissued some of them and I don't know if they are the same as the old ones, but it became a bit of fun haunting used book stores to find CYOA books that we didn't already have in our collection. If I think of anything funny at that general reading level, I'll post it too.
