I imagine a lot of people out there find they have little to no use for one or more of Lightroom's "modules" as they are currently implemented, and luckily, Adobe built all of these things as dynamically loadable plugins which can be removed from the application bundle and thereby exorcized from the interface altogether. I have found this to have the beneficial side-effect of reducing Lightroom's launch time and memory usage as well.
In my experience, immediately after launch, Lightroom consumed 113MB of "real" memory and 322 of virtual (note that this figure as Apple reports it includes any memory used by shared libraries and is not usually terribly meaningful). After I yanked out the "Web" "Print" and "Slideshow" modules, these numbers went down to 66MB and 296MB respectively, and the application launched noticeably faster. Obviously the heap can and will grow with further use, but it should remain at least a little bit leaner than it would have been otherwise.
If you find yourself in the same boat as myself and want to trim a little fat, just use the Finder to dive into Lightroom's "Package Contents", drill down into /Contents/PlugIns and trash anything you don't want (might want to make a backup before you do this just in case you change your mind later). I'd leave Export.agmodule and XML.agtoolkit alone as they are likely critical to several aspects of the application's functionality you wouldn't want to break.
