This is not an original idea. A couple of friends from other areas presented this as a fun challenge. Recently, at an event others suggested it. So by "popular demand", here it is:
This one should prove to be a bit easier than the last. To find this cache you will need to find 36 caches, and they can be at any time in your caching career.This challenge requires a list of your qualifying caches (details below). If your log is not accompanied by the required list your find will be deleted! Simple as that.
Cache is an ammo can; inside you will find swag starting with each letter of the alphabet, please be sure to leave something that starts with a letter of the alphabet.
The physical cache is placed in an area that represents the Best of Geocaching to those of us who have been in the hobby long enough to remember how it was.
Now for the Challenge – You must successfully log a find on a cache that begins with each of the 36 alphanumeric characters, i.e., A-Z and 0-9. Only the first character of the cache name is used, as follows:
Cache -- FALLEN WALL CACHE can be used for “F”
Cache -- The Fifty States Colorado can be used for “T”
Cache -- 2nd Place Street can be used for “2”
The following examples cannot be counted:
Cache -- "Chillin' with the Troll King" is not a valid cache (because it starts with ")
Cache -- $#!+poke is also not a valid cache
Note that you may NOT use caches you own (even if you found them some time ago and have since adopted them). Since cache names can sometimes change, be sure that the names still fit the requirement you are trying to fulfill as of the date you log your find of this challenge.
To document your successful completion of the challenge, you will need to create an ordered list of the 36 caches found in your log entry using the following format:
* 0 - Cache Name - GC_____ - Date Found
* 1 - Cache Name - GC_____ - Date Found
(all to way to the end)
* Y - Cache Name - GC_____ - Date Found
* Z - Cache Name - GC_____ - Date Found
The Rules -- This one is meant to be for the fun of it, so we're not making a whole lot of rules. But, there are a few:
1. You may not count any cache that you have hidden or have ever owned.
2. There is no time frame for the cache finds, so if you like, all of your current finds count toward completing the challenge. This means that you may already have the challenge completed without even trying. But, you can always impose your own start date and start from scratch. I will leave that up to you, do whatever makes you happy. Remember that this is for the fun of it.
There will be no "FTF" prize or "honors" given out just because you were fortunate enough to have "immediate qualifications" or time & resources to carry this out in "record-breaking" time - This does not prove anything -the real prize is the fun you have along the way and the friends who share the path. But you are welcome to do the "dance". 
3. In the interest of fair play you will not need to find all of the caches in the sequence, you will be allowed one "wildcard" that can replace any letter or number you have not found, but it can only replace one cache. You do not have to use the wildcard, which makes your log even more impressive!
There is a physical cache at the posted coordinates but the challenge doesn't end there...be prepared for more fun.
Go to Geocaching Etiquette for more information