Picture gallery of some of Rogue Dwellings' work:

http://www.flickr.com/photos/davetwodaves/sets/72057594074763580/

http://picasaweb.google.com/RogueDwellings/Tipis

http://www.flickr.com/photos/65263310@N00/

Some links to good people doing good things: 

http://tipilife.net

http://emergencycommunities.org/

http://www.lomakatsi.org/

http://www.sheltersforfreedom.org/

Here's a link to Linda Holley's excellent and comprehensive site about traditional and historical tipis:

http://www.tipis.org