I like these things. DuckDuckGo has them as "instant answers" and you're encouraged to add new ones:
https://duckduckgo.com/?q=roll+4d4%2B4
Wolfram Alpha also supports it (see example at bottom), but much slower:
https://www.wolframalpha.com/input/?i=roll+4d4%2B4
Google and Bing support dice rolls, but not the rpg-syntax.
Still waiting on my answer :(
daniel@pancake:~$ duckgo roll seven dice --- Type: Exclusive Answer: Answer: ", , , , , , " Type: dice_roll