I would tell you, but I'd probably get tarred & feathered. So rather than do that, I will attempt to skirt around my (preferred) direct answer.
Ah, what the heck. Edited later to add content.
Here's what I do.
If the neck is really dirty and/or the fingerboard really dry (finished maple doesn't count here), I remove the neck and use 0000 steel wool and General Finish's Orange Oil to clean and nourish the wood and clean the frets. This may take 3-4 passes, wiping down with paper towels between passes. Once clean, a final dose of Orange Oil is applied and allowed to penetrate a few minutes. I finish up by wiping down again with paper towels. I'll clean the back of the neck with whatever is appropriate for its finish, then finish up with wax.
That's for the tough jobs.
For general maintenance, I'll use wipes such as Wonder Wipes regularly and Orange Oil at string changes.
The neck is removed so that I have no worries about steel wool shards & dust getting into the pickups or electronics. Even with really good masking, there is still the remote possibility that the steel dust can work its way into the pickups and abrade its way into the soft windings (sorry Brad).
Note that while 0000 steel wool is abrasive, its effect on fingerboard wood as described above will be to burnish (polish) it rather than actually remove material. The combination of Orange Oil (which cleans and lubricates) and steel wool on fingerboards is a great cleaner that can pull out really nasty layers of grunge. It will leave a nice satin sheen on frets. Also, the Orange Oil I use will not dry wood out and there are no special handling precautions necessary for towel disposal.
If you're trying to remove tarnish you can go over the fingerboard with 0000 steel wool but mask off the pickups first so you don't get steel fibers in them. That'll make your fingerboard look like new.
What he said ^^ mask off the fretboard and pickups and use wire wool to clean them, then use lemon oil or wonder wipes or whatever to give the wood a good clean.
I like to do a little preventative stuff-- I try to wash my hands before I play, and I keep my strings clean.
When the frets need cleaning, I take my bass to a shop where they have a little tool that fits over the fret, and get a string change. Though I must say I'm interested in that steel wool method above, and I'll be trying it.
Since I don't have access to lemon or orange oil that won't dry the board, I use mineral oil, which was recommended to me by a luthier. Old English and rosewood don't get along.
I like wonder wipes, but I think they're a little too convenient. I enjoy taking the time to take care of my stuff, so I'd rather put time into it.
i think he asked what we used to clean our frets...
i use my dremel with a cotton polish head impregnated by that orange polish agent thats in the dremel package..
just tape some cardboard over the fretboard (with nonstick tape) to be sure no accidents happen.....
mind you i still havent needed to do anything to the frets on my musicmans though
It will be VERY Strongly attracted to the magnets in the pickups...both from above and below. You really won't be able to get all of it off if it migrates inside through the pickup covers or down between the pickup and the body.
You might consider something non-metallic. Perhaps metal polish (e.g. Flitz), with masking tape on the fretboard to protect it, or a Scotchbrite pad, also with the wood protected.
Sounds like you are no closer to getting the answer you were looking for!
I use blue masking tape to cover the fret board (neck removed from body of course) then I will go at the frets with some very fine steel wool. Then I use a light compound with a dremel using the polishing bit, this process really makes the frets shine. Once this is done I will remove the tape then give the fretboard a deep cleaning with a good oil ( I sometimes use Dr. Ducks). This process is only done maybe once a year. If you wipe down your bass each time you play it that will help keep things fresh.
Also, cleaning the neck when you change strings will also help prevent a gouked up fret board.