I used a Nashbar suspension-corrected rigid fork on my 26" MTB for awhile. Never had a problem with it. It can handle up to 3" tires I believe. Has both canti bosses and ISO disc caliper tabs. Also has fender eyelets. The only thing is that it looked a bit odd with so much space between the tire and the fork crown. I think they're going for $49 these days, but they regularly sell out of them. I had to wait a week or two when I ordered mine before they got more stock to ship one to me. Looks like they're in stock right now, though. The rake is 45mm.

http://www.nashbar.com/bikes/Product...28_-1___202440