I use the Sigma 30 mm f/1.4 on my D40x for low-light parties. It has the advantage of being an HSM lens - Sigma's equivalent of AF-S.
I also use the 50 mm f/1.2 and 35 mm f/1.4 manual focus lenses for when there is not enough light for autofocus - manual focus lenses tend to be easier to use than autofocus lenses in manual. I have a modified K3 screen in my D40x for this purpose.
Sorry for the delay replying, your question slipped by me.
Of the lenses I mentioned the Sigma 30/1.4 is the only one that won't cover FX sensors (Nikon's name for 'full frame') or 35 mm full frame. The other two were designed for 35 mm full frame, so they will cover both FX and DX.