From The Web Atom:
System Ninja Portable is a program for cleaning your computer of unwanted junk that constantly slows your entire system down. Apart from the useful file cleaner, the program also has a Startup Manager, Process Manager and P3P Registry History cleaning tool. System Ninja Portable features a powerful scanning engine designed to locate junk files on your computer, wherever they are hiding. System Ninja looks at a files creation time, file extension, location and many other factors to determine whether it is needed by your computer.