Update: here's some I've found
- Ebonmuse, On Cryonics
- Ebonmuse, Who Wants to Live Forever?
- Why we'll never be downloaded
- Why Minds Are Not Like Computers - actually there's quite a lot of scholarly writing arguing that the idea of simulating a brain on a computer is not merely impractical but impossible in principle.
- Michael Shermer on cryonics
- Skeptic's Dictionary on cryonics
- Cryonics–A futile desire for everlasting life
- Quackwatch - Is Cryonics Feasable?
- Ben Best - Debates about Cryonics with Skeptics (Best is President/CEO of the Cryonics Institute, but this is a snapshot of a debate on the James Randi forums, with a link to the original forum debate)
- Frozen Stiffs, Ruth Holland, BMJ 1981