Are there any custom digital pens for wacoms out there or just the standard one it comes with?

You can get a different tip (maybe more than one now) that gives a longer action when pressed down - I learned about it when I asked about a more brush like action from the pen - the tips are in the parts area. Because of the electronic interaction between the pen and the pad, it is highly unlikely someone would make a custom pen - whatever you mean by that.