As part of the gsoc-mashups project I've implemented the Flickr gallery controller which would allow you to create a image gallery using the WYSIWYG editor. Gallery supports pagination and you could filter your images based on author, tags or photosets.
You can have a look at the sample here : http://www.web2media.net/sstheme/gallery/
You could see the code of the mashups module, if you got SVN access: svn://svn.silverstripe.com/silverstripe/modules/mashups
I would appreciate your feedbacks on code and any ideas on implementation.