Anyone ever fish three flies at once for steelhead?

I usually fish a tandom rig for trout using two flies but have not yet attemped three. Is there a lot of tangles? My hypothesis is the more flies the bigger the chance! Increase the odds, why not?

I have never fished three flies, but do routinely use a dropper.  Bowhunter is right about fishing multiple flies where the fish are stacked.  A tandem or triple is a recipe for snagging fish.  One of my favor and very successful tandems is a sucker spawn with a nymph dropper.  The nymphs that I typically like are copper johns, brassies and pheasant tails, usually beadheads.  I also like to use a woolly bugger with a glo bug dropper.  One thing to keep in mind is the length of the leader between the primary fly and the dropper.  I usually like to keep it less than 20 inches and more than 8 inches.  I tie the leader into the eye of the first fly most of the time.  I sometimes tie the leader onto the bend in the hook.
 
Another thing to keep in mind is adding some shot to the leader between the first fly and the dropper.  This depends on the water depth and flow. 
 
Good luck and have fun.

there was 32pg "nymphing for trout" add-on to the sept 2007 Fly fisherman mag...it has a lot of useful info!!
 
they describe and picture the process of bottom weighted bounce nymphing.. here's the link
http://www.flyfisherman.com/rmwest/ltbouncenymphing/index.html
 
i can assume that it would work well in erie tribs, and i plan on trying it out this year
 
i have fish 3- bugger-- ss--- pheasant tail
you really have to watch your "casting"... it becomes more of laying you line
i don't do it regularly... it was more of a test of "could I"  instead of  "should I"
 

I have noticed while fishing a multiple rig in clear water, that a larger attractor (bugger) will catch an eye and then the strike will come on a trailing nymph

you will definitely snag more fish that way, and when you break off you'll lose three flies.