Total newbie here so please excuse the sloppy descriptions and terminologies.
I bought my K100d Super a little before Christmas and I'm loving it.
Last week I viewed a post by distorted_vision which featured extension tubes. While searching ebay I came across a fisheye lens which screws on to my existing lenses. It's just a cheapy by Precision Design. I think it was only $70.00 (US). I attached it to a old short lens I have. Its a SMC PENTAX-M 1:2 50mm. No auto focus, just manual. Well, I don't know if I'm correct in my assumptions but it almost appears to have worked a little like an extension tube as well by letting focus a little closer then before to the subject. Anyway, enough rambling... here are a few pics.
btw, #1 was converted to B&W via Google Picassa and #3 was converted to B&W via CS2.