[Vaupell]

Dont know if it helps or you can implement this yourself..

but in anycase Sourceforge.net = tools of the trade
they have everything, including atleast 10 of those convertion thingys

if you can implement a java file your self, then here is a good one
http://sourceforge.net/projects/jconvert/

appears to only have 1 dev, and wery few errors
which also is availible for publick display.

And does this converter have to be availible just in the forum or in a post option
if you just want it on a forumpage, it makes the whole thing alot more acoomplisable
howewer if you want it postbit enabled, phew .. gonna need some help on that

check it out. GNu license.