This site lists them all, by state - Awesome!
In PA we have -
Allegany Geotrail http://www.alleghenygeotrail.com/
This is actually 11 challenges in one. There is a coin for each county that you find 6 caches in, then an additional coin if you complete all 10 counties.
Allegany River Wilderness Island
a 26 mile stretch of caches located in the water - would make a GREAT two day kayaking trip!
Get your passport at one of 3 locations, find 25 caches
Butler Freeport Trail
I LOVE it when the passports can be printed ahead like this!
They request a $10 donation when completed, to receive the coin
Legends of Conservations Geotrail
Collect all 30 cards. Coin is not trackable, I've been unable to find a photo of what it looks like. We do have a couple of the cards. :-)
Mainline Canal Geotrail
Logbook here - www.mainlinecanalgreenway.org%2Fdownloads%2FLogbook.pdf
Brand new - just started June 1st, in time for GWS11
" If you want to earn a commemorative NCT 2011 Medallion, you will need to find 50 of the 100 caches and get the hidden code word written on the inside of the lid of each cache. There is a coder sheet you can download on the cache pages. Find the cache, get the code word, write it down on your coder sheet, and once you get 50 caches, you can submit it to the ANF Chapter communications director for verification. If the codes match, you will receive your Medallion. There are only 100 Medallions being offered, so first come first served."
South Mountain Geotrail
Get your passport at these locationas - http://smgeotrail.blogspot.com/p/rules-guidelines.html
Clearfield County Geotrail
The Clearfield County Geotrail is now open. Log onto www.geocaching.com to get the official cache cordinates, register now its Free! 2011 theme is cemeteries of Clearfield County. First you need to pick up an official Clearfield County GeoTrail Passport book, then you need to find 25 out of the 30 geocaches spread throughout the County. At each geocache location there is a unique stamp to use inside your passport. After collecting 25 stamps you can bring your passport book into our office or send it in for validation, then we give you a unique wooden coin for completing our geocaching trail.