I have an old version of Norton Cleansweep and it seems to do everything it claims and backs stuff up as well in case you change your mind. I let it delete things and then delete the backup later.
I don't know if it's still available as a single product though, you might have to buy Systemworks which is no good if you don't need the other components.
RegCleaner should take care of the other stuff uninstallers leave behind but, you need to be clear that you understand what you're doing before you use it. Also, the writer of RegCleaner now recommends that you use the Registry cleaning tool in his jv16 PowerTools, which he says, is safer to use. Check out his site;
http://www.vtoy.fi/jv16/shtml/jv16powertools.shtml
I am not by any means an expert or a power user and I have used both these tools without problems (so far!). Registry cleaning, done incorrectly, will screw your system up big time. It is not a 'one click' solution to your problems and the program cannot decide for you what is or is not safe to delete.