That depends on what YOU want to be doing 5 years from now. Do you want to continue to be an admin? Then you might consider going after a certification such as MOS or CAP.
If you think you might like to branch into web page design, learn HTML.
If you think you might like to break into database design, master Access.
If you want to change careers but don't know what you want ot pursue, then you might want to wander through the Department of Labor web site (if you are in the USA) at
http://www.dol.gov/ to see what the anticipated careers in demand are going to be.
For myself, I will probably learn a new programming language like PHP, being used now in web design. (but that's MY path)

Marie