The pending release of RavenNuke™ 2.4.0 includes nukeSEO™ DH, which uses nukeNAV™ to enable modal popups for overriding the key HEAD tags for a page.  It does this using the jQuery plugin ColorBox.  nukeNAV™ also enables modal popups for user login and search.  But this powerful addition also enable lightbox functionality with either single or grouped images (i.e. for a gallery).  And it's really easy, too!

Here's a sample: