Dragons Blood does quite a fast job of covering and area. Mine is grown mostly in shade nowadays, and that doesn't seem to slow it down. It still gets red in the winter, but is mostly green in the summer, probably because of the shade. While I haven't grown it as a ground cover, sedum Angelina is a fast growing sedum that roots where ever it touches so I can imagine it being good too. It stays more green than yellow when grown in the shade. I'm using sedum Alba in another area as a ground cover. It's not as fast spreading as Dragons Blood, but it is denser and still pretty fast and looks good.
Although not a sedum, yellow ice plant, Delosperma nubiginum, is very fast growing, dense and mat like in a vivid bright green.
