How can I use my Blender models on Irrlicht?
Irrlicht supports a plethora of formats, choose what works best for your purpose.
.x is quite good as it supports animation (you can download .x and blend for comparison here: http://www.s-fonline.com/webhosting/dhenton9000 ).
Collada is probably worth a try and my3d-format is great for lightmapped architecture.
BTW, both forums have a search function:D