"Macros" on a Mac.... Wow have I been stumped???

I just talked my Uncle Mike into buying a kick *** Imac. He is very fond of it, as am I, because he has been ******** about how bad Windows is for about 10 years. Anyway he asked me a question that I couldn't solve. he called it "Macros"

Basically he wants to assign a line of text to key commands. For example he wants to be able to hit Command + (any letter) and have it input a line of text (like http://www.youtube.com/watch?v=qRVzRtqJnaw ... which is my latest video if you are interested).

Anybody know if this is possible?

Gary