SharpKit is only free as long as you want to use it for projects that don't need it (the limit is like 2k lines or something). When I last tried it I was not very happy with the code it generated. Additionally, it uses the standard mscorlib so it is not unlikely that you will end up calling methods that are not implemented (which is the very problem the tool is designed to avoid). If it were open source, I would have contributed to SharpKit instead of rolling my own, but it is not.
When it comes to the language support, I think Saltarelle is slightly ahead, as it supports goto and yield (I don't count SharpKit's implementation of yield which translate 'yield return "x"' to '$yield.push("x")' and then returns the $yield array).
Thanks for the reply, This seems to be a very nice tool. I will definitely try it out. Though I don't think that I will switch unless debugging is implemented (via source maps) like SharpKit has. This is invaluable to me at times.
When it comes to the language support, I think Saltarelle is slightly ahead, as it supports goto and yield (I don't count SharpKit's implementation of yield which translate 'yield return "x"' to '$yield.push("x")' and then returns the $yield array).