imgur is great for the purpose of sharing images alone. But dropbox has many other uses, sharing any kind of file, backing up stuff, syncing devices which gives access to your notes/scripts/passwords/portable apps and their settings, collaborative group-syncing, hosting html based websites and a bunch of other stuff :p +1…
I personally don't like attachments just because the way my browser handles them. It opens them in the same window and when I click back any post I was working on is gone. It's killed more than a few critiques I've been working on. It's a pain to right click and choose "open in new tab" bahh... if it eats my post I don't…