IFC Exporter on Sourceforge
Autodesk Exchange Apps - IFC Exporter for Revit
There have also been a few quite a few posts on other blogs about IFC recently. Here is a selection:
Using two different versions
I alternate a bit between 2012 and Revit 2013 for optimal import results. Have not quite decided yet on what is best. 13 works faster, but I've seen a bug on windows which I love. Right now I use the 2012 imports, and so do I upgrade the file to 13 afterwards.
Using ADT as a middle-man
If an item ... Certainly will not be exported correctly, you can isolate it in a view, export view'et to 3D DWG for ADT and send it to the IFC from ADT. Boring... but it works. I've done this on an entire parking garage with a fall in all directions and had to realize that the correct 3D geometry, after all, it is very important.
via Google Translate of http://revitnorge.blogspot.com/2012/04/revit-2013-og-ifc.html
Improved ArchiCAD Connection Add-In for Revit ApplicationsFree Add-In developed for use by Autodesk Revit programs in the Structure and MEP disciplines. This application is recommended for use with IFC-based model exchange between GRAPHISOFT ArchiCAD and Revit applications. The Add-In for Revit applications variously enables direct import of ArchiCAD IFC models and IFC model export to ArchiCAD, or serves to optimize Revit’s standard IFC import and export functions used to exchange data with ArchiCAD.
Revit Add-Ons: GRAPHISOFT Interoperability Downloads
DP stuff: IFC Export - Revit 2012 (describes various problems with 2012 IFC)
DP stuff: Update - IFC Export -Revit 2013 (issues improved in 2013)
All Things BIM: IFC Export from Revit: Reply
I’ve been monitoring the discussions in the Industry Foundation Classes (IFC) group on LinkedIn for some time now and recently saw a post criticizing IFC export from Revit 2012. I saw a few discrepancies in the methods described in the blog post, so I decided to run through the same tests myself. ...
Geometry Gym - Revit import Grasshopper IFC addon
You can test for yourself. Here's the grasshopper files used in the demonstration and some example IFC output.. You need to download the latest plugins from http://www.geometrygym.com/downloads