We use to have a Dice Roller. Unfortunately, it was very short-lived.
I think it was a bit buggy, but don't take my word for it.
No clue on if it's coming back in the future or not, though I agree that it would be nice to have back.
If you nedd to, there is always Random.Org, a simple site that I use for mine, and a few other sites floating around that can help you out.