Here are some screenshots from my tree generator/editor.
Everything you can see here is realtime generated with LOD,
animated ( with some wind ) and rendered ( even for the forest ).
Framerate is about 10/15 fps on my PII450 with geForce
for the forest ( up to 256 trees ) with not optimised openGL
rendering. As it's part of my job at Infogrames, I can't
tell you a lot about the technical things ( it's secret at the moment ).