My Wife babysits occasionally for one of her co-workers and they love video games, so whenever they come to our house I let them play my PS2 or PS3. The last time they came over they complained about a lack of fun games (kids these days...

) in my collection so I offered to go by GameStop and pick a game they'd enjoy to playing. They picked Monster Jam (I bought it used so I could return it after they went home) and we went home and played it. They absolutely loved the game. Every time they come over it's all they want to play. The game isn't bad (they usually make me play for them, they like watching more than actually playing, which makes for a kind of weird scene when the wife walks in and her husband is playing video games in front of a bunch of kids) and Amazon had a buy one get one free sale a while ago so I decided I'd get this as my free game for the kids to play.
So, for those with kids that are interested in games and monster trucks, this is a pretty good choice for you. The game isn't hard enough to frustrate little kids on the easy difficulty, but it can also entertain the older ones on the harder settings. Plus, it's pretty cheap now adays so yo won't be hurting your wallet much.
Parker
1st Gen 60gb PlayStation 3, 320gb PlayStation 3, PlayStation Vita, 120gb Xbox 360 Elite

Thrustmaster T500RS, Astro A50's, Obutto Ozone Cockpit

Classic Game Room: 16-Bit, 100% Awesome