[highsea]

About 6 months ago posted a Show HN for WhenToExchange http://whentoexchange.com it shows currency exchange rates and keeps track of large price moves that make it favourable to exchange one currency for another.

Didn't receive much feedback, but still use it personally when shopping online and booking travel.

[nitemice]

Just found this and I love it. Going to be using it a lot from now on.