ArcMap MXD to ArcIMS AXL Conversion
Once you delve into the ArcXML Programmer’s Reference Guide you notice that the cartographic capabilities of ArcIMS are increased, when compared with those offered in through ArcIMS Author - ArcMAP provides a solid UI to define your map service symbology, whereas to take advantage of the symbology options not available in ArcIMS Author, you must update the ArcXML code directly (using a program like TextPad).
As ArcIMS also supports raster marker symbols, which aren't available in ArcIMS Author, I have found the following script to be infinitely useful:
http://arcscripts.esri.com/details.asp?dbid=12766
This script outputs an AXL file based on an MXD. Note I have found that some of the symbology does not carry across entirely, so if using this utility you will likely have to do some tweaks (sometimes polygons receive polyline symbols...) - I find that this tool is especially great for theming different classes of polygons and symbolizing point layers with the ArcGIS symbols.
By the number of downloads recorded, I am not the only one who finds this script invaluable – thanks Jeroen!