Took this freaky test I found on Ammar’s blog:

.DLL?
“Constantly in danger of bringing down the house?”
I’m not even sure what a .DLL is!
I want to be a JPG :\

Update:
A DLL is “Dynamic Linking Library”.
Simply it’s a file which contains functions used by many applications, So instead of duplicating the code with each application you install, It’s kept in a *central* location which can be accessed and used by all of the applications.
So I’m very useful :P 2al “bringing down the house”.
(Thanks Mohammed Sameer!)