In no particular order:
Robert Webb's Great Stella Program. and Minesweeper-3D
Ulrich Mikloweit's beautiful polyhedral models,
Dr Richard Klitzing's facetings of Uniform Polyhedra. Dr Klitzing has also produced this Wythoff Kaleidoscope and this Waterman Point Set generator.
Alex Doskey's Polyhedral Pages. The Doskey Toroids, an amazing library of Stewart Toroids, Diamond Regular Polyhedra and the Uniform 3-D Honeycombs amongst others. Alex is also the US distributor for Jovo Toys.
George Hart's huge site (specifically his Virtual Polyhedra) includes uniform polyhedra, Johnson Solids and compounds. It also has an interactive prism maker and a page for generating polyhedra from their Conway notation.
Vladimir Bulatov's pages include uniform polyhedra, Johnson Solids, a stellation composer, Polyhedral Mirrors, the plates from Brückner (1906) and much more.
Roger Kaufman's Polyhedra. Including Hedron Tools , 108 Degree Rhombohedra , Triamond Regular Polyhedra and Uniform Compounds of Uniform Polyhedra amongst others.
Adrian Rossiter's open source Antiprism software.
Dave McCooey's Java Applets for Visualizing Various Polyhedra
Pedagoguery Software have produced a set of die-cast polyhedra.
Melinda Green's page specialises in Infinite Polyhedra and Hyperbolic Planar Tesselations
Don Hatch's hyperbolic tessellations (amongst others), a hyperbolic tesselation java applet, Tyler and his amazing $20 holohedron!
Professor Branko Grünbaum's home page with pdf files of many of his papers.
Mason Green's scaliform polychora and geometry pages.
Fr Magnus Wenninger's Home Page and biography
Steve Waterman's mathematical pages.
Sándor Kabai's Mathematical Graphics
Hironori Sakamoto's World of Uniform Tessellations
Craig Kaplan's project page includes Symmetrohedra and Near-miss polyhedra.
Maurice Starck's 'ride through the polyhedra world'
Paul Gailiunas's paper on "Twisted Domes" (PDF), as presented at Bridges 2004.
Jonathan Bowers's Polychora (4-D) Site
George Olshevsky's 4 Dimensional Polytope Page
Eric Weisstein's polyhedral pages at wolfram.com
Dr R. Maeder's Uniform Polyhedra
Guy Inchbald's polyhedral topics
Mark Fleurent's Polyhedra
Dominique Nguyen's Java based Polyhedra Viewer
Tom York's program, "The Many Faces of Polyhedrons"
Jorge Rezende's puzzles with polyhedra and numbers.
Rob Strange's "astro-logix" polyhedral construction kit
Steve Dutch's page on Symmetry Crystals and Polyhedra
Zvi Har'El's Program to generate the uniform polyhedra
Stephan Werbeck's Dodecahedral Constructions
Chris Lomont's mathematical screensavers
Dymaxion Projector: Buckminster Fuller's icosahedral map of the Earth (needs Quicktime)
The Geometry Junkyard
My real world polyhedron
models are made from Polydron.
Please e-mail me if you find any dead links on this page.