How can I make a Silverstripe module that will build a database table that comes pre-populated with several records? (A look-up table, for instance).

Any ideas on this? I know it can be done.

Have a look at the Blog and Forum modules - by default they create Holders and example posts / threads etc

/**
	 * Create default blog setup
	 */
	function requireDefaultRecords() {
		parent::requireDefaultRecords();
		
		if(!DataObject::get_one('BlogHolder')) {
			$blogholder = new BlogHolder();
			$blogholder->Title = "Blog";
			$blogholder->URLSegment = "blog";
			$blogholder->Status = "Published";
			
			$widgetarea = new WidgetArea();
			$widgetarea->write();
			
			$blogholder->SideBarID = $widgetarea->ID;
			$blogholder->write();
			$blogholder->publish("Stage", "Live");
			
			$managementwidget = new BlogManagementWidget();
			$managementwidget->ParentID = $widgetarea->ID;
			$managementwidget->write();
			
			$tagcloudwidget = new TagCloudWidget();
			$tagcloudwidget->ParentID = $widgetarea->ID;
			$tagcloudwidget->write();
			
			$archivewidget = new ArchiveWidget();
			$archivewidget->ParentID = $widgetarea->ID;
			$archivewidget->write();
			
			$widgetarea->write();
			
			$blog = new BlogEntry();
			$blog->Title = _t('BlogHolder.SUCTITLE', "SilverStripe blog module successfully installed");
			$blog->URLSegment = 'sample-blog-entry';
			$blog->setDate(date("Y-m-d H:i:s",time()));
			$blog->Tags = _t('BlogHolder.SUCTAGS',"silverstripe, blog");
			$blog->Content = _t('BlogHolder.SUCCONTENT',"Congratulations, the SilverStripe blog module has been successfully installed. This blog entry can be safely deleted. You can configure aspects of your blog (such as the widgets displayed in the sidebar) in the CMS.");
			$blog->Status = "Published";
			$blog->ParentID = $blogholder->ID;
			$blog->write();
			$blog->publish("Stage", "Live");
			
			Database::alteration_message("Blog page created","created");
		}

Perfect. That's exactly the code I was looking for. Thanks.