Filler games that go over well with my students:
Memory games (lots of powerpoints where kids look at a picture for 20-30 seconds, and then it gets covered and students have to answer a question about it, like, "How many clouds were in the sky?" or "What color was Ryan's flower?")
Bingo
Noonchi (all students stand up, and students must count from 1 to whatever, but if more than one student says the same number together or if anyone says the incorrect number in the sequence, they must sit down -- the winner is the last one standing).
Scattergories
Spot the Difference (getting shown two seemingly identical pictures, and having them point out all of the differences between them)
Rock, paper, scissors (when I'm the one challenging them -- you can have a lot of fun with this, especially if you actually introduce penalties/rewards).
Classroom Boggle
I also have mind puzzles and give them a time limit to solve them. They get candy if they manage to solve it before time runs out. And then I show them how to solve it.
I haven't tried it, yet, but I've thought about having quick and simple origami lessons, too, where they have to follow simple instructions.
Wordsearch puzzles always seem to be popular, too.