There are a lot of webpages doing this. Please search a bit.
I can put up a page for that too, but that will be overkill.
For example, itouchmap.com/latlong.html
there are a lot more using OSM/google map etc.

I came across another good one: http://www.findlatitudeandlongitude.com/

--
Yours sincerely,
Dipanjan Chakraborty