My son can't get enough Legos. He wants new sets every year for birthday and Christmas. They have sets to go along with almost anything the boys could be interested in, too: planes, police, fire, trains, just tons of stuff. My kids love card and board games, too. Maybe baseball cards and an album to keep them in. Remote control cars was a very good suggestion, too.
When my son was younger (around the 7 year old stage) he loved Rescue Heroes. I don't even know if they still make those, but something similar might be good.
I'm always big on getting my kids something that in not computer, TV, or video game related. Games, puzzles, sports equipment (football, backyard volleyball set, wiffle ball set, etc), painting/drawing supplies, or anything crafty. (I always joke with my kids that I enjoy when they're grounded because they find so much fun stuff to do! LOL)
If you're looking for things with a little bit higher price tag, do a search for Electronic Snap Circuit Set. It's a battery powered snap together set with which they can make a functioning AM radio, lights, a fan, all kinds of stuff. Erector sets are cool, too, and Magnetix or GeoMag sets are neat. And every single year my kids get a book of some kind, whether they want it or not! LOL
I hope I at least gave you some ideas to run with and that you find the perfect gift for them both!
Merry Christmas!