Trouble with modelling in Second Life

I'm fairly new to Second Life at the moment, but the building and modeling possibilities that it offers are the things that attract me the most, not the over-hyped social meta-whatever… The one thing that I still can't figure out is how to import custom-made models, such as those from Blender for example? Does anyone know? Thanks.

You can't really (*really*, actually) import externally into SL, the idea is that you need to use the default tools that the world provides – the polygon count needs to be kept in check, you know… the lag's bad enough as it is
However, there are ways around this, I've heard of plugins for modeling programs that effectively simulate the SL tools on your machine offline, so that you can play around with stuff and then import it back in…