I recently obtained two low resolution spectral gratings: a 100 line/mm grating from Patton Hawksley company in the UK and a 200 line/mm grating from Rainbow Optics in the US.  Both come mounted in 1.25 inch diameter cells and can be screwed onto the nose-piece of a CCD camera or webcamera just like a filter.

It is very interesting to obtain stellar spectra using these filters. I have only begun to look at the spectra of the brighter stars so far, but others have recorded spectra of very faint stars... even supernova spectra in other galaxies have been recorded with this technique with accurate tracking and sufficient exposure time.

Here is my first attempt to record the spectra of a bright star... I chose Arcturus: 

http://webzoom.freewebs.com/revans_01420/Equipment/arcturus-lrs.pdf

In the future, I hope to spend more time on this exciting area which seems to be seldom explored by most amateur astronomers.

Other Stellar Spectra:

Vega:  http://webzoom.freewebs.com/revans_01420/Equipment/vega-spectrum.pdf