I'm not sure what reading level you're looking for. There could be a huge gap between appealing to a reluctant second-grade reader and an eager, gifted, third-grade reader. I've tried to present a wide range of books.
Mrs. Piggle-WIggle by Betty MacDonald
Einstein Anderson by Seymour Simon
Encyclopedia Brown by Donald J. Sobol
Beverly Cleary
Gail Carson Levine (her Princess Tales series is a lighter read than her other books and isn't particularly girly despite the name, her other books are denser and have more depth)
Roald Dahl
Boxcar Children by Gertrude Chandler Warner
Liza, Bill & Jed Mysteries by Peggy Parish
Sisters Grimm by Michael Buckley
Secrets of Droon by Tony Abbott (the main series are pretty fast reads, the special editiobs are denser and more intense)
Wayside School series by Louis Sachar
The Wolves of Willoughby Chase by Joan Aiken
Kate Klise
From the Mixed-up Files of Mrs. Basil E. Frankweiler by E. L. Konigsburg
How to Eat Fried Worms by Thomas Rockwell
The Westing Game by Ellen Raskin
Bruce Coville
The Phantom Tollbooth by Norton Juster
Green Knowe series by Lucy M. Boston (gets pretty intense, may be scary)
Misty of Chincoteague by Marguerite Henry
Pippi Longstocking by Astrid Lindgren
Danny Dunn series by Raymond Abrashkin and Jay Williams
Ben and Me by Robert Lawson
Animorphs by K. A. Applegate (gets intense)
Call It Courage by Armstrong Sperry (may be intense)
The Secret Garden by Frances Hodgson Burnett
Just-So Stories by Rudyard Kipling - the language is beautiful but dense. I would recommend for a read-aloud, but an older eager reader might enjoy it.
I second reading aloud. My kids were bookworms and were in gifted and talented programs. Reading together was something we enjoyed doing even into high school, when their schedules allowed. You could also do recorded books, but I prefer reading ourselves.