I sometimes do this sort of thing using marquee selection and alt-click-drag. This creates copies that you can move around the same layer. You can also use the marquee to select an area and do transformations, color adjustments, etc. on it. The main problem with this is that you can't do overlapping stuff. If you want that you'll have to do overlapping bits on a new layer. Still, it works pretty well. Clone stamp looks like it's pretty cool as well but I haven't used it much.