You're more than welcome to use any of mine, although I think this is also an interesting discussion point!
Iv done a few guides and talks where I have used peoples sites as examples; in some situations Iv asked permission but in others I have not. It's a very fair argument that a site is public and therefor can be freely viewed by anyone in any context; HOWEVER there is a flip side to that argument by saying that highlighting a site in the wrong context could get it unusual any maybe unwanted attention.
In your case I don't think that an othercon would get the wrong sort of attention, but I would be curious to hear general opinions.