My subsite creation webpart lets the user choose from a list of allowable site templates. Of course, SPSiteCollections.Add() wants the internal template name, like "STS#0" for a team site template, and bog only knows what for a custom site template. My users don't like this much; they want to see "Kewl new subsite template" in the dropdown selection, and my boss doesn't even understand binary, so he agrees. So here's how you convert the template title to the internal name:

 // We want to create the site using a pre-defined site template.

// People refer to site templates by using the public template name,

// but SharePoint refers to them by using the internal template name.

// Find the internal name for the desired site template.

string InternalTemplateName = "";

SPWebTemplateCollection webTemplates = globalAdmin.VirtualServers[0].GetWebTemplates(localid);

foreach(SPWebTemplate t in webTemplates)

{

    if(t.Title.CompareTo(strPublicTemplateName) == 0)

    {

        InternalTemplateName = t.Name;

        break;

    }

}

// If the template could not be found...

if( InternalTemplateName == "" )

    throw new Exception( "Cannot find site template '" + strPublicTemplateName + "'." );

// Create WSS project site.

SPSite newSite = siteCollections.Add( url, title, desc, localid, InternalTemplateName, login, name, email );