We have used them in the past with fairly good results; especially for light duty. They work well for blind locations as you mentioned and in thin material where you can't tap a hole. If your application is light, harbor freight has an assortment pack for ~$10 which is much more expensive than rivets. But if you are planning for a connection that you can remove without having to drill it out each time, they can be quite useful.
http://www.harborfreight.com/cpi/cta...temnumber=2972