Bruce Byfield at Linux.com – Sun Presenter Console extension is useful but undocumented:
"After installation, you will not see any sign of SPC except in the Extension Manager. To use it, open your slide show in OOo Impress and go to Slide Show -> Slide Show Settings in the menu. Under Presentation monitor, select the display on which the audience will view the presentation. Once this setting is configured, SPC will start automatically on the other display, making it visible to you, but not to your audience."