How do I do it? I'd like to export some of the models I've created in Bryce into, say, an .obj, but I don't know how to go about doing it. I group the object, and go to file, but export is always greyed out...any ideas?

I dont think you can except through the object presets list, which exports as *.obp or through the terrain editor

Here's how you do it. If the object is exportable, ie: Any imported mesh, native terrain or symetrical lattice. Click on the object to export, next click on the little "E" for Edit that is visible when the mesh is selected. This will open the Edit window displaying two spheres (one rough, one smooth). Now push (Command) D on a Mac and probably (Alt) D on a PC. This will open another window with export options. If you are exporting and imported mesh you can change the format if you like from DXF or 3DMF, to OBJ, 3DS, among others. Select the format you want and click save. If you are exporting a terrain there will be a different window with more options for exporting textures along with it. I hope that helps you, good luck.