Elastizell Corp.
We manufacture cellular lightweight concrete and lightweight fills. Elastizell is America's Industrial leader in cellular concrete applications for: Insulating Concrete Roof Decks, Engineered Fill Geotechnical Applications, and Non-Structural Floor Fills
http://www.elastizell.com/

Advanced Lightweight Engineering
Specializes in design, development, and production of lightweight structures. Based in the Netherlands.
http://www.lightweight.nl/

Tensys
An engineering analysis consultancy providing specialist services for the design and construction of lightweight stressed membrane structures worldwide.
http://www.tensys.com

Pylons
A lightweight framework emphasizing flexibility, with developer choice of its major components: database, templating, user interface, and dispatch. [Open Source]
http://pylonshq.com/

Cellxion
CellXion designs and manufactures a full line of concrete, structural steel, and ultra-light aluminum shelters. In addition to shelters, CellXion provides specialty products such as cell-on-wheels, cell-on-chassis, and tower trailers. Services include equipment integration and complete turnkey construction.
http://www.cellxion.com/

Windmill Associates, Inc
USA. Design and manufacture of lightweight braider carriers, drive components and replacement parts. Detailed parts catalog, including prices.
http://www.4windmill.com/

Construction Computer Software
A single-package, project control system for the construction industry, designed by estimators, quantity surveyors, civil engineers, project planners, architects and other construction professionals . The Estimating, Valuations, Planning, Cash Flow and Forecasting components integrate all aspects of a project’s construction process.
http://www.ccssa.com/

Tri-State Laminates
Tri-State Laminates SIPS is a manufacturer and marketer of laminated products and components offering a complete line of expanded polystyrene foam core structural insulated panel systems (SIPS) to the homebuilding and commercial construction industries.
http://www.tri-statelaminates.com

LGI (Lightweight GUI Library)
A Lightweight, cross-platform GUI library and application framework. Currently 3 ports exist, Win32, Linux and BeOS. [Open source]
http://www.memecode.com/lgi.php

California Lightweight Pumice Inc.
Pumice - Suppliers of pumice, lightweight concrete, lightweight backfill, lightweight aggregate and pre-cast block products
http://www.clppumice.com/