Here are all the signs I commonly see in RP:
-s- Meaning: Short Post; apologizing for a short post
-d- Meaning: Done with post
-c- Meaning: Before last post
>>> (or) >> Meaning: These are usually used when typing a paragraph in Feral Heart. People use these because there is a limit on how much you can type
/(words)/ Meaning: Usually put before a thought or used to add emphasis to a word. Examples would be /I wonder what I will find today/ or /you/
"(Words)" Meaning: The ", or a quotation mark, are used around words when a character is speaking. Examples would be: Eclipse sat down and looked at the nearby creature. "Why hello there!" She barked.
>(words)< and <(words)> Meaning: When someone uses >< around a sentence, it's meant to be in a whispering tone. Usually when a character is telling a secret. <(words)> Is the exact opposite, and is used to show a character is yelling, or shouting.
*(words)* (or) -(words)- Meaning: Those are used to show action in some roleplays. An example would be *sits*, or -sits-. Not all RPs do this.
I'm not quite sure what -vs- means, perhaps very short? Eh, I'll have to look into that.
I hope I'm not forgetting any... >.>