Gaiman is fast becoming one of my favourite writers. I first encountered his work via one of my other favourite writers, Terry Pratchett, with whom Gaiman collaborated on the excellent Good Omens, a typically Pratchettesque - which pretty much just means funny and irreverent - novel about the apocalypse.
From there, I bought Neverwhere, an absolute must-read for anyone who's spent any time traveling on the Tube. American Gods was borrowed from my local library, and I just purchased Smoke And Mirrors with a gift card that the exquisite Mrs Doombreed gave me for Christmas.
He's worth checking out, if mindbending weirdness and challenging, intelligent fiction is your cup of tea.