This is the process on a computer.
Rightclick on picture. Save to your dropbox public folder.
Doubleclick on Dropbox's icon on the task bar. Open public folder.
Rightclick on picture. Get link. Paste it here.
All done from the desktop. Takes about 20 seconds.
On the iPad.
Click and hold on picture in Safari. Save picture to camera roll.
Get on Wifi connection, switch to Dropbox app, and wait for it to scan and save the picture to the Camera Uploads folder. God forbid if you have a bunch of other pictures waiting for an upload.
Move picture from Camera Uploads to Public folder. Get public link.
Leap from Dropbox back to Safari, and paste link to forum.
While I was exaggerating about the whole process taking 10 minutes (it barely takes 3), it's so much more cumbersome to do on the iPad. And that's mostly due to the way iOS is set up.
Also, nice broken link to your picture.