I don't think you will find one (but I have not done that much research into it) ... there are options though, albeit not perfect solutions, but options none the less. You could go with something like this
here ... but I think it is just for older IPAQs ... or something like this
herebut that is getting more into the custom application area ( I don't know what would be needed for this to actually work) ...
here is another one
here Anyhow ... that is my 2 cents
Greycat