View Source on the iPhone (snoopy.allmarkedup.com)

Mobile Perf from Steve Sonders has this, as well as many other features - Firebug Lite, Page Resources, Docsource, Web Timing, DOM Monster, Storager, YSlow, SpriteMe, CSSess, and Zoompf

http://stevesouders.com/mobileperf/mobileperfbkm.php