When referring to internet usage a d-bag could describe:
1. Anyone who uses a blog
2. Someone who posts comments on YouTube
3. People who constantly change their status update on facebook
4. Anyone who even knows what the fuck twitter is and why its relevant
In summary, anyone who uses the internet assuming that their life, thoughts and opinion are of any value to other people...
A: "Hey, I just went to Europe and wrote a blog about it, you should check it out..."
B: "Did the people in Europe realize what a d-bag you were or did they encourage you to become one?"
A: "This video is so funny, I seriously LMFAO =)"
B: " I can see the video just fine without reading your fucking comment...If your not a 12 year old prepubescent girl you probably shouldn't use gay tag lines...d-bag"
A: Hey, did you guys hear about this new thing called twitter?
B: Yeh, I can't believe they made something gayer than facebook...
A: What?! But celebrities write what their thinking and thats really important for my well-being...
B: You're such a d-bag