Thanks for posting this, Millipede - a reminder that we are in peak tick season.
In college, I worked in a Lyme Disease research lab for the New York State Dept of Health, so I know a tick and how to kill it when I see one. Looks like you found a few common dog ticks (Dermacentor variabilis ). Do you or a neighbor have a dog? That's most likely how these creepies wound up on your patio.
For those of you in the continental US and southern Canada who have pets and enjoy the outdoors, you should check out these links from the US Centers for Disease Control in Atlanta. There's info on tick-borne zoonoses, preventing tick bites, and protecting your pets.
Rocky Mountain Spotted Fever: http://www.cdc.gov/ncidod/dvrd/rmsf/
Lyme Disease: http://www.cdc.gov/ncidod/dvbid/lyme/
I live on Long Island - Lyme Disease Central - and I don't let it deter me from my walks in the woods. I just take precautions (wear light colored clothing, use DEET repellent, tuck pants in socks) and check myself thoroughly when I get home. Enjoy the outdoors, but take precautions and check yourself, your children, and your pets for ticks.