It's a terrible thing to have to admit.
After all, addictions aren't something to be glib about or joked over, unless you're Karen Walker. It's time consuming and money consuming. It takes you away from reality and all your friends. Eventually you find that you've spiralled downward and your choices are rehab, or self destruction.
I have discovered my own addiction. It's shameful to admit.
I'm addicted to Wikipedia.
There, I've said it. It began while reading Buffy scripts (another shameful admission). I realized how many offhand references Joss Whedon puts into his scripts and needed a way to quickly cross reference them for full impact. Pretty soon I had both screens up each time I indulged. Then I found myself checking other information -- book synopsis and backgrounds, movie plots and character backgrounds, historical references, snippets of lyrics or poems I needed to identify. One night I found myself clicking link after link looking up Harry Potter non-canonical references. Hours later, in the middle of an article on Bellatrix Lestrange I realised I have a problem.
I can cross reference for hours. There is so much interesting information out there are the click of a button! Summaries of science concepts I probably won't understand otherwise, word usage, entymology.
I could go on forever. But I won't, because I need to look up something.