My wife has a cold air setting on her hairdryer, but it's not powerful enough for some of the dust. If you are worried about your stickers, constant vigilance with a plastic fiber duster seems to be a great option. I worry about the abrasiveness of canned air or an air compressor on stickers over a long period of time.
If it's just vehicles, no problem - just use a feather duster and/or Swiffers (or the cheaper no-name equivalent) - but if you've got a bunch of figures standing up (and even a modest army builder like myself has enough to make that a hassle) it's nice to have another option.
I've used those compressed air canisters people use to clean computer keyboards, though I haven't bought one in a while. Someone on another forum I visit mentioned a hairdryer, which I think its a BAD IDEA unless you've got one with a really low and cool setting. Excessive and directed heat can not be good for your GI Joes.
Specifically I've been using a handy feather duster and no-name Swiffers. I don't mind moving everything around because I've been in a constant state of finding "the perfect display" which is difficult because I only have 2 1/2 shelving units to work with, and of course there's always new stuff coming in. I don't like cluttered displays so I find myself having to change things up a lot, and I dust when I do.
I haven't tried this, but it seems physically sound as I think about it. What if you had a fan focussed on your collection at all times. (Energy cost would not be that much higher and a decent fan goes for $10 at Walmart). I imagine the constant flow of air would not allow the dust to settle in the first place. Conversely, and air purifier might take a good protion of the dust out of the air in the first place. Other than that, nothing but constant vigilance would solve the problem, which gives you the excuse to spend quality time with your collection! Of course, the other extreme is to pull a Gattaca every time before anyone enters the room, as dust is mostly made up of human tissue.
Swiffer Dusters, lint free cloth, and sometimes armor-all cleaner (NOT regular armor-all) depending on age and condition.
Qtips.. and I found these cool Qtip things my wife uses for makeup that have pointy tips.. so I'll snag one of those everyonce in awhile.. but normally, just a damp cloth(mainly for figs and larger vehicles with little or no stickers), swiffer and Qtips.. that's what I use.