I've tried a lot of the recommended apps I've never heard of and really liked crap cleaner.
Anyway, For those of you who want to run ccleaner on a USB key (without installing it on someone's computer) here is how:
First, Install ccleaner on a computer. When it asks where to install it choose your removable usb flash drive.
Next, Open notepad and copy and paste the following (not the including quote).
regsvr32 /s CCSubtimer.dll
regsvr32 /s CCTreeView.ocx
regsvr32 /s CCListView.ocx
regsvr32 /s CCTab.ocx
regsvr32 /s CCHelper.ocx
Save that file and call it CCleanerRUN.bat
Put that file in the ccleaner folder on your usb drive where you installed it.
Then when you want to run the program just run this little batch file...no need to 'reinstall' it on the other persons computer. A small time saver.