It generally doesn't take people long to realize there are a lot more emoticons coded into this forum than what show up in the emoticon task bar. You would be correct. I love them, and I add new ones all the time. I cannot tell you how many there are because (1) that would require me to manually count them, which I do not have time to do, and (2) I add new ones all the time as I find some that seem fun. Here are come common questions and answers:
Q: How many hidden emoticons are there?
A: As stated above, I cannot tell you how many there are because (1) that would require me to manually count them, which I do not have time to do, and (2) I add new ones all the time as I find some that seem fun. EDIT: As of August 22, 2012, there are approximately 491.
Q: How does the code for a particular emoticon get decided?
A: I decide how to name it based on a variety of factors. Sometimes, the right code is obvious. Sometimes, it is an inside forum joke. Sometimes, it is dependent on my goofy sense of humor. Sometimes, there is a logical connection to a forum member. Beyond that, it is hard to provide a more specific answer.
Q: Is there a complete list of hidden emoticons and their codes?
A: Yes. But it is in the admin section. If you are not a forum admin, you cannot see it. A few users have taken it upon themselves to compile runnings lists.
Q: How can I get an emoticon named after me?
A:

In all honestly, the process is completely arbitrary. If there is a logical connection between an emoticon and a particular user, whether because of the user's forum ID, their real name, their interests, their posting habits, or some other logical connection, I may name an emoticon after the person. For example:
Tick has:
:tick:and
:tick2:because his forum ID came from the comic character and because he is old. Both logical connections to him. The fact that he had two named after him shortly after he joined wasn't because of favoritism or because he was good at begging. It just made sense. Nevertheless, begging and bribery do not hurt your chances.
Q: Why do some have a colon at the end, while others do not?
A: No good reason. Convention on a lot of forums for code is to have the code initiation symbol at both the beginning and end, so I just kind of fell into that habit when coding them. But early on, I went with the standard codes for a lot of them, which did not have a colon (or other symbol) at the end. No real good reason other than that.
I will update this FAQ periodically, but that's probably a good start.