I'm specking out a set of servers to handle a sharepoint 2007 install and a number of ASP.net applications. I was wondering if there were any issues running additional websites on a machine or cluster which is running the web front end portion of sharepoint.
I don't think it is a problem, as long as you use separate Application Pools for each site. I have seen people run into issues when they have SharePoint and other web apps running in the same pool.
This also depends on how resource intensive your SharePoint site and your web apps are of course.
You can even run different web apps inside your SharePoint IIS site - just put the virtual directory in a different app pool, then setup SharePoint to exclude the path as in this article: http://support.microsoft.com/kb/828810
Sharepoint is VERY resource hungry, I wouldn't bother running anything else on the same box as the sharepoint admins will complain that these are what is causing the site to run slowly.