I have 2 external hard drives, 3 printers, 1 scanner and 1 external CD/DVD burner - all attached via USB.
In addition I have 2 multi-port hubs - 1 four port and 1 seven port which are both powered. Most of the equipment is through the 2 hubs. {You can't have too many USB ports}
I have an E-machine desk top with 4 USB outlets in rear and 2 in front. It's one year old.
My 20" Dell LCD monitor also has 2 USB ports. I try to keep these for flash drives because they are very accessible.
I have been using USB flash drives for several years. My first one cost about $50 and was all of 128 MB.
I'm not sure you can even buy one that small anymore, as most are 1 GB and up nowadays.