I have been using CCleaner for awhile now and I very much like it.
Although there is one thing that I would like to see included in it. Recently at my work (a university) we have been hit pretty bad by a few viruses. One of the things that I like to do after removing said virus is to make sure that all temp files, temporary internet files, etc. are all removed.
Now CCleaner works great on the prof systems and any other single user machines, but on some of the shared lab machines there are many users. It is a very daunting task to remove the temporary internet files for all of the users manually when there are more than 40 there.
I know that there are other tools out there that are capable of this so I would love to see the option to select which user accounts you want it to clean. It would also make things much easier for me to remotely clean some of the machines as well.
So really just the addition of being able to detect and choose multiple users accounts on the same system would be great.