I've been using Scirra's Construct 2 (http://www.scirra.com/construct2) and like it so far. I do programming for my day job but I like how this abstracts things that I need to do to make a game like tying art assets to game rules so I can focus on the game design and less time on learning lots of subsystems.

Curious to hear about other game engines as well.

I highly recommend Construct 2: http://www.scirra.com/construct2

It takes care of most of the heavy lifting when developing games for HTML5, but it still has a very open and powerful scripting language (unlike something like gamesalad which is more like using pre-built blocks).

Edit - Ha, beaten by 1 minute.

Have you made anything using it yet?

Current favorite: ImpactJS. Closed source, costs $100 to get started, but comes with a nice level editor and a very involved community.

Great for making 2d games.

I'm liking create.js and easel.js

I like gameQueryJS.com as there's almost no learning curve if you know jQuery.