Well, keenspace has the ***include filename*** tag to let you easily put the same thing on various pages, and change the contents of the included file to reflect the change to all pages.
To get multiple comics going, you could always set up 1 keenspace account per comic, and have a main site link to the others.
Also I've heard rumors of sites that have more than one comic but don't know the details. I think Gav once talked with Kaichi of kyokipress about setting him up for that. Dunno what came of it.
<A HREF="http://www.kofightclub.com" TARGET=_blank>Ko Fight Club</A>
<A HREF="http://comicollage.keenspace.com" TARGET=_blank>Comicollage</A>