Today, I had 5 blades on me. However, two of them are on my keys (Spyderco Honeybee, and a Swisstool Utilikey), and weight nothing, so I generally don't count them. The other 3 (today at least) were the blade on my Gerber Mini-Suspension S in my front right pocket, my Spyderco UKPK clipped to the change/lighter pocket of my jeans, and my Buck Vantage Select clipped to my front right pocket.
I usually stick to this 3 blade system if I'm out in public...the MT is always on me, and I use it for the tools not the blade, but I always try to have a small, people friendly knife on my person. Either a traditional slipjoint, that UKPK, or my Byrd Robin usually ride shotgun to my larger blade. The biggest knife I usually carry is a Byrd Cara Cara/Cara Cara 2, which goes in my right butt pocket, again paired with a smaller knife in another pocket. Unless I'm carrying my Stainless handled Cara Cara, the total weight of blades on me never exceeds...oh, maybe 6-7 oz.
If I'm around the house, and I know I'm not going out, it's usually only one blade, which varies depending on my mood.