Gift for a 5Yr Old Little Boy...

Some simple but fun ideas are:

Bubbles, Sidewalk Chalk, Playing cards, binoculars, Hotwheels or Matchbox cars, Tonka trucks (the small ones aren't too pricey), kids' DVD's like Veggie Tales, 3-2-1 Penguins. Travel toys for his age group should be easy to find, and aren't that expensive. Play Dough kits are usually a hit and are educational as well as fun.
Also dominoes, anything Legos, board games geared toward that age group (keep the slip, so parents can return if they already have it, and then they can get something else).
And amazingly enough, a gift card from Target, WalMart, or Toys R Us, has always been a winner in my experience.

MatchBox cars, boys love cars.

If his parents aren't opposed to them, Nerf guns are always fun for boys that age. Also things like a compass, canteen, hikers guide book..something along the lines of exploring. I have a 10yo son & I know that I prefer things that get them outdoors & off their kesters.

Those shake-and-go cars are a hit and are inexpensive. They are fun to race also! :)

I have 4 boys, the twins are 5 right now. You can't go wrong with a car or truck toy. Hotwheels has some neat little playsets out right now that are great gifts and within a classmate budget.

My son's is 4 1/2yrs and been addicted to hot wheels since he was 18 mths. He use to just love the cars but now he loves the different track sets. A set of the 5 cars makes him just as happy though. He also loves megabloks, trains, construction vehicles, remote control cars, and anything with Lightning McQueen or Spiderman on it. Just some suggestions.