hey Joey, I agree with Zurf and Deadstring. For the most part, I think you'd be fine... it's the few "members" here and there that don't quite know how to converse on the forums (or don't want to) that might email her ... everything else of course is open for you to see. For the most part, she could easily access everything she wants and NEEDS to access right here, and just use your email. That way anything that happens behind closed doors, is actually open to you! If you think she'll be using the forums and posting often as well, you may want to introduce her to us with her new profile (using your email... so any lurker that might hear she's 13 still can't reach her directly) so we can be vigilant about knowing who she is, and that she's a teen, and remember to treat her appropriately (although, I think everyone gets treated pretty appropriate anyhow... as you know, almost all Chordian's are respectful and friendly!). OR you could simply email me, and I can give the mods a heads up privately if you don't want to introduce her to the general public. Give her the reminder that this forum IS open to the public... so even non-members can read it, no posting too much personal information... she need NOT put her location in her profile... especially not putting too much personal info (pictures, age, sex, address, name of the school she goes to, etc... ) But of course, you already knew that.
My son is on chordie, a few years older than your daughter... he doesn't post very often. He reads the forums though, and mostly just looks up songs and saves them to his own songbooks.
If there were ever anything that you were concerned about, being parents ourselves, the mods would happily help you out. Feel free to email any of us, or you could report a post and there is plenty of space to put your reason for reporting it. I can think of a lot LESS safe places for teens to hang out online. Ultimately, it is your decision if you'd like to allow her to have her own profile... or hers if she decides to get online somewhere that you aren't watching. IMHO, they will find a way ... I think it's better to allow it with supervision, than to wait for them to figure out how to do it themselves without supervision.
Amy