I didn't see this (but I suck at searching so forgive me if it's been done to death) but it seems there are a lot of peeps on here with Webcomics. As we all know guest comics can be a GREAT way to promote yourself and cross-promote your comic as well. They're the ultimate win-win.
I finally am at a point where I feel comfortable in opening up my own at WaywardSons.net to a guest comic. If you head to the homepage now you'll see what I'm looking for... which is pretty much anything. BUT since this thread may go on longer than that homepage link stays there, the real link is HERE to the blog posting about it...
What I'm suggesting for THIS thread is not a listing of "Hey I'd like to do a guest strip/comic" but a listing of people who wouldn't mind GETTING a guest comic for THEIR Webcomic site.
This way, the thread can continue on without getting cluttered and people can PRIVATELY contact (either through this message or through the respective Web sites) to discuss doing a guest strip.
Hope that makes sense...?