For general purpose cleaning of metal tools, I use a combination of a little bit of Awesome ($1 store citrus cleaner - probably cheap GoJo equiv.), WD40, and 3-In-1 Oil on a rag. I find this works great for providing surface protection in wet environments and also helps cut light rust.
For plastic handles and for most of my power tools, I use a combination of the Awesome, WD40 and a TINY bit of trichlorethylene. I find that this helps strip out any deep grease and dirt on handles, etc. After cleaning with trichlor, I ALWAYS wipe down all the plastic surfaces with a bit of Awesome and motor oil or 3-in-1.
For tools that may have acquired a heavy coat of rust, I will generally use oil and steel wool in most applications. For those applications where a tool is severely rusted, I use phosphoric acid. I try to use acid based cleaners as a last resort when cleaning tools, as they definitely take a toll on any finish.
As a general rule of thumb, any tool I clean with any sort of chemical (WD-40, citrus cleaner, etc.) will always get cleaned and coated with a thin film of heavy weight oil afterward for rust prevention.
I definitely like the idea of a Mr. Clean magic eraser for cleaning handles. I have always been surprised at what it can clean around the house, just never used it on my tools. Perhaps its time to change up my methods.