My favorite part is having access to edit someone's node directly.
This is a powerful tool, and one that must be wielded with utmost care. One of the greatest differences between Everything2 and Wikipedia is that not just anybody can come by and edit your hard work as they see fit. This is why I write for Everything2 and not Wikipedia, and why Everything2 has an article on hydropulpers and Wikipedia does not.
Used without due respect for an author, the ability to edit someone's node can raise some extremely bad feelings, I'm sure. This is why the administration has chosen to give only a few users they can trust access to this feature. I have never edited a currently active user's writeup without permission. This is the sort of thing that can only lead to trouble: mistrust, hurt feelings, power struggles, complaints to the administration... things I don't want to see happen to Everything2.
So I have used it sparingly, but when I do, I find it the most powerful tool in the editor's arsenal. It's certainly more powerful than having infinite votes and C!s, and much more versatile than the ability to nuke a writeup.
When a user has been gone for several months, I can take it upon myself to make some corrections. Sega Dreamcast controller port repair had a minor factual error which I corrected with the strikethrough tag and an editor note. Typos, misspellings, and formatting problems I simply correct. In any case I sign the node with an <!-- HTML comment --> in case the user comes back and notices it has been tampered with. The nice thing about this is that I can now make even minor corrections that before I would have felt overly pedantic about submitting to Broken Nodes.
New users have also benefited from this. Often, a new user is unfamiliar with the formatting and linking procedures here, or may be unfamiliar with the finer points of HTML such as definition lists or proper use of the PRE tag. Sometimes it can be difficult to explain what they need to do in the limited confines of the /msg box, and it would be easiest to just show them. After obtaining permission, I can directly edit their work, leaving <!-- HTML comments --> in my wake explaining what I did. I've helped out a number of new users this way, and Everything2 can benefit from their new skills.
I also recently completed a node audit. There are a number of ways to potentially go about pointing out things that need correcting in a large number of nodes: I could have sent a large number of /msg and flooded the inbox. I could have copied things into an e-mail. I could have listed things in my scratch pad. None of these really seemed convenient for me or my auditee though, so I obtained permission to add <!-- HTML comments --> where I thought corrections were needed. To the outside viewer, the writeup was completely unchanged, but to the author the text input box below detailed everything I wanted to note in one place, each conveniently right next to problem area itself.
Finding creative ways to use my editor features is what makes this job fun. Doing it for the benefit of Everything2 is what makes it rewarding.
themanwho also suggests using the E2 Annotation Tool for ease of making large numbers of corrections. This has the significant advantage of being available to non-editors.