I found a simple-but-brilliant little site the other day, driven (as I understand it) by the BBC’s backstage.bbc.co.uk API initiative. Simply go to mtraffic.org/M4 for the very latest traffic alerts on the M4 motorway – and yes, if you change the URL to any GB road number of your choice, you’ll get the latest for that road too. The interface is very much back-to-basics, and is aimed at mobile phone use – but (probably as a direct result) it’s so usable, I’m finding it a handy resource on my desktop too.