After SFO in 2009, Sooze and I rode Route 66 from Tulsa to Chicago. There is some really neat stuff along the Route!
In Litchfield, IL, is a little place called the Ariston Cafe. Check it out - it's been in operation since 1924, is family-owned and -operated (we've seen three generations there at one time!), and the food is pretty damn good.
If you're in to Diners, Drive-Ins and Dives, one of the places Guy visited is in Vinita, OK, and is called Clanton's Cafe. It's pretty cool.
There's the usual stuff - the Blue Whale, World's Largest Totem Pole, the gas stations, etc... They're all cool to visit.
In Cuba, MO, are some cool murals. Also in Cuba is what was the World's Largest Rocking Chair, and although I believe that specific honor has been taken by the town of Casey, IL (which has a bunch of 'World's Largest' stuff, if you're into that kind of thing), the gift shop (at the one in Cuba, MO) has some good Route 66 stuff. Just watch the gravel in the parking lot - it's deceptively deep.
Somewhere out there, there are Route 66 GPS POI listings and routes. I used both in 2009. Take a look around - they're prolly still out there somewhere. I may still have 'em, but that's been a toasted HDD or two since then.