My wife loves the Elfa Platinum hanging shelf system. They make stuff that's suitable for use in civilized living spaces and looks sharp. They also make stuff that's useful in the garage and basement. Everything uses something called Easy Hang Top Track, which is a mutant cousin of DIN rail that gets solidly attached to the wall and then the shelf standards (or garden tool hangers) get connected to that.
Elfa sells screws for their shelves, including drywall anchor stuff, but sometimes you want something different. Or maybe you're like me and consider drywall anchors to be a last resort for light duty use only. We just put some top track up in the closet in the craft room with 2 1/2" wood screws into the studs. The stuff in the basement is hung up with [Tapcons[(http://www.tapcon.com), which are definitely on the list of my favorite things ever.
Anyway, there's no clear guidance on what size screws to get on Elfa's web site, since they want you to buy their stuff. You want #12 Philips countersunk wood screws, or 3/16" Philips Tapcons, in length to suit.