Thanks to Ricky Cadden for pointing us towards the brand new beta of OwnSkin's Professional Theme Creator. It's a 100% online theme creation application for S60 smartphones, i.e. no messing around with Java tools or having to install an SDK. Be patient while it's loading up, it'll take a minute or so to load into your desktop browser but the end result's well worth it. Finished themes can be shared directly or simply downloaded as SIS files for your device.