from their site...
Opacity is an easy to use program for drawing graphics for the screen. It's great for making resolution independent images and icons for applications and the web.
You can download a free trial of Opacity below, and the full version is available for $89.99. Opacity Express, a streamlined, more affordable version of Opacity, is also available for $39.99.
http://likethought.com/opacity/It is not as robust as flash is, thats for sure, but I bought a copy specifically because it is cheap and it has html5 support... i am hoping that as time goes by it will get even better.
best of luck with your creative work, and hopefully there will be even more tools that let you draw easily for the web that have a good chance of being free.
e.g. here is a free html5 tool for drawing...
http://mugtug.com/sketchpad/:hi: