It's about time I get off my lazy ass and do something. I love modding, and though I took a little break from it, I think I am going to startup again, but start off with something real easy.
While I figured I could make a completely seperate .esp for this, I figured it would be better if it was related to my current mod, but i want it to be optional. While I could .esm-ify my .esp for the mod, I have heard an .esm is essentially the archive for all the items and other things that make up the mod, while the .esp basically contains the data where the player actually plays. Aside from that I don't think you can modify a .esm in the CS, you'd have to constantly switch from .esp to .esm to .esp to .esm to make it work properly and to modify it. I am sure i might be wrong, but, you get the point.

Basically I just want to add a small addition to my mod that is totally optional...I would prefer it not to use a .esp but still be optional, but I am pretty sure that isn't possible...I would liek to use the least amount of .esps possible because I don't want someone's LO filled with with 6 different .esps just for one mod (I hate it when modders package their mods that way!) because it means more chances of conflict and more numbers bringing you closer to that limit.
So basically, to my knowledge, the easiest way to make it dependant on the mod is to just have a seperate .esp. I am sure this is relatively easy to do, but I don't want to accidentally make any mistakes. So, unless there are better ideas to make this easier and more convenient in the long run, the please educate me on how to create and .esp to .esp dependancy. I noticed one of my mods actually says "requires xxx.esp".

ESP-ESP dependancy is actually done quite easy.
You're lucky in so far that the difference between an ESP and an ESM for Oblivion is just an internal "flag", thus filename and extension doesn't matter.

So to make one plugin dependant on another, ESM-ify the master, open the new one together with the master, use something from the master in the new one (this makes it dependant) and save.
You can now ESP-ify the master back to its original state and it will still be the master for the new plugin you just saved. Only drawback is you have to do the ESM-ify step every time you want to open the new plugin, due to a bad weakness of the CS, or it won't know anything from the master anymore on open.