ArcIMS is indeed nice, but I find the javascript client hard to customize. I wrote some perl to generate ArcXML requests and parse the responses; then just linked to the URL of the generated image. Then I found an easier approach if I just wanted the image: ArcIMS supports the OpenGIS Web Map Server specification which let me specify everything I needed in the URL and returned the image. Simple, but it is not enabled by default.

A cheaper solution with the 60% of the features that are needed by 90% of the people is the UMN MapServer. It is free, works well, and supports perl out of the box.