I'd focus on SQL, and C#. Learn those well as you will likely be able to transfer your knowledge there across the board with other programming languages and scenarios.
In the IT department where I work, there are all types of apps I could write for them.
I'd suggest just helping them out and write apps for them based on what they lack or currently pay for that would be easy to rewrite. Things such as password storing app (that encrypts people's passwords) rather than storing their passwords on their desktop in a .TXT file, stuff like that. Create a few apps like that to gain experience.
If you create a password storing app (in a DB somewhere) thats encrypted, and write the UI for updating/storing/retrieving, etc you will find out really quick that it's a much bigger task than you imagined.
Intel Ivy Bridge 3550, AsRock Z75 Pro3, 8 gig GSkill 1600 8-8-8-24 timing, Crucial m4 64gig, 500meg WD RE4, ATI 7970 3GB, LG IPS236V x 3, Windows 8, Antec Sonata Solo 2, Antec 550watt PS.