I've just created a plugin for Rage Software's WebDesign 2.3.x that will allow you to add an event in a three-column HTML concert/event list like the one on my Shows page (where the three columns are Date, Artist and Venue). The plugin will allow you to add up to five artists and one venue (with links). This plugin is licensed under a Creative Commons Attribution-ShareAlike license.
Download a tarred-gzip file (*.tgz) here: add_show.tgz (1.4KB)
Here's a screenshot:

Known issues:
1) As mentioned above, I can't seem to get the plugin icon to show up in the menu... no matter what I do.
2) add_show only supports up to five artists as of right now... that's all I need.