You can now go to Google and ask it to tell you the current Hijri and/or Hebrew date, as well as ask it to convert the dates for you. I tested some examples and for the most part is works pretty well. Danny Sullivan from Google said on Twitter that this was "recently added" to Google.
So for example, if you want to know the current Hebrew date you just go to Google and search for [hebrew date]:
If you want to know a date in the past, like the Hebrew birthday of this site, you can put in a specific date:
If you want to know when a Hebrew date falls out on an English date, you can Google that too (although, I tried 10 Nissan with two S's first and it didn't work).
Same works for Hijri:
Forum discussion at Twitter.