Thanks for all your input on the previous diary entry. Many of you have indicated that you'd be more than willing to help moderate the spam diaries. Some of you have suggested making it only delete if multiple people mark it as spam so as to avoid possible mistakes. I think that's a good idea, but is a little more tricky to implement than the method I was thinking of, which would be one person simply to delete. However, my plan was exactly as MissTick had mentioned in the last comment (at time of writing :)) which was that diary wouldn't actually be deleted but would be hidden. This is how I presently do it anyway when I do it myself so most of the coding for that side of it is done. The deleted diary user would NOT be able to login however, so they couldn't restore the use of their diary, I would need to do that if it became clear it had been deleted by accident/malice.
Maliciously deleting someone's diary is unlikely since I would personally vet every person who has the ability. If you've been on the site a while and want to participate I'll probably let you, but each deleted diary would be logged with the username of the person who deleted it and any malicious deletions would ultimately end in the revocation of the deleting rights. Accidental deletion could be possible so I'll try to build in an 'Are you Sure?' screen.
Thanks for the feedback folks, I'll get to work on something as soon as I can – 6 week old twins permitting