Yes, they do provide a good amount of UVB and are nice and bright. Not all are created equally though and it's worth investing in a good bulb and fixture. I've done testing with some of them and the lower end bulbs are pretty poor (especially National Geographic brand). The best I know of are MegaRay and Arcadia. These bulbs are good for providing heat and UVB to a basking area from about 12-18'' up depending on the wattage and brand. They have a limited range to the sides though.
Another good alternative for UVB is to use a T5 tube with a reflector. This allows you to create a gradient across the enclosure and provide basking level UVB across a large area which makes it easy for your dragon to regulate and bask. The heat and bright light comes from a basking bulb so it's a two bulb setup. This is what I use and it works well. Both MVB and T5 are very good ways to provide UVB to the enclosure, they are just different approaches.