The customer I'm working for now required that for a particular area template, that the document library has content approval on by default. I thought that wasn't really a tough requirement (and it ain't if you know where to look for and know the (undocumented) syntax) ;) So here is a step-by-step guide to get a document library that is created during the creation of a site with content approval (and versioning) on by default:
1. Open the SCHEMA.XML file in the folder 60\TEMPLATE\1033\\LISTS\DOCLIB and make the following adjustments:
a. <List xmlns:ows="Microsoft SharePoint" Name="Documents" Title="Document Library" Direction="0" Url="Document Library" BaseType="1" ModeratedList="TRUE" VersioningEnabled="TRUE">
b. Add the views "My Submissions" and "Approve/Reject items" between the
i. Locate the view "Allitems" and change the property to DefaultView="FALSE"
ii. Locate (baseviewid=4) the view "Approve/Reject Items" and change the property to DefaultView="TRUE"
2. Copy and paste the file Allitems.aspx twice and rename the copy's to "mod-view.aspx" and "my-sub.aspx"
3. Do an IISRESET on all webservers