On Dale White's Memory Made Easy site, there is some great footage of him memorizing a 28-digit number in 75 seconds! This is apparently a successful world record attempt, but there is no indication of any officials present to verify the record.

This video is from a site selling a memory course, with which I have no experience. Any questions about the course itself should, of course, be directed to the people who run the site.

Video Format:
Windows Media