Parts Libraries

Trace Parts - Library of parametric components for 2D/3D CAD assemblies, which can be used with several CAD packages.
http://www.traceparts.com/

CADClick - A database for mechanical engineers that offers access to CAD geometries from different suppliers on mechanical engineering.
http://www.cadclick.de/

Oh Yeah CAD - A free online parts library that supports AutoCAD, Solidworks, TurboCAD, and SolidEdge native file format.
http://www.ohyeahcad.com/

Catalog Data Solutions Inc. - Online 2D/3D parts library hosting, integrated with PTC Wildfire and the ability to do Parametric searches. Formats include PRT, DXF, IGES, DWG.
http://www.catalogds.com/

PARTserver - A parts library integrated with many CAD systems for direct invocation, as well as with standard data formats
http://www.partserver.com/

CADRegister - A source for design professionals, engineers, and architects to download component drawings from leading manufacturers, in a variety of industry-standard formats.
http://www.cadregister.com/

Vanguard Software GmbH - Offers partsCAT, an electronic spare parts catalogue software for publishing catalogues on CD-ROM and online.
http://www.vanguard.at/en/

Archiforge - Free 2d, 3d cad models, textures, a gallery with projects as well as information about the latest architectural competitions.
http://www.archiforge.com/

PARTsolutions - A parts library integrated with many CAD systems for direct invocation, as well as with standard data formats.
http://www.partsolutions.de/index.asp?sid=2

VirtualCAD - Free 3D CAD models in tandem with Free manufacturer part number interchanges. Supports all major CAD systems.
http://www.virtualcad.com/

Catalog Data Solutions, Inc. - Solutions to add 3D models to online catalogs and CAD modelling consulting.
http://www.catalogdatasolutions.com/

CADSymbols - Online 2D/3D parts library for Solidworks, AutoCAD and other software, in formats including ACIS SAT, DXF, DWG, and IGES.
http://www.cadsymbols.com/

CADParts - Produces library symbols and footprints for the Cadence CAD software.
http://www.cadpartsusa.com/

Design Celebrity - Virtual design library for architects, interior designers, decorators, space planners, and design consultants..
http://www.designcelebrity.com