www.currencycalc.co.uk
I
first decided to do an online Currency Calculator about 10 years ago,
but finally got around to getting something set up about 6months ago!
Currently, it takes it's data automatically from a SecretSource every 24hours or so, and there's a couple of scripts on there so people can integrate the information into whatever systems they like.
There's also a couple of online conversion / calculator tools.
Like most of my personal projects, I lost interest in this site shortly after I did the hard stuff (getting the automatic feeds and writing the integration scripts), however at some point I will get around to finishing it off - it's nearly there anyway.