Tiago Medeiros tutorial show (actually not new, maybe just forgotten) a nice custom LOD technique, and he explain it very well with rich useful notes. Example scene (Max 2010) also included. Glad and hope to see more tut's like this online ;) The original Portuguese version (Google translated English version).
P.S. - A few hints -- if using target camera, link the control object (the sphere) to the camera target object and bind (with Wireing Params or script controllers) the sphere radius to the camera distance and fov.