All sites shared here need to meet one criteria. That I find them to be family friendly. I will visit people's sites to make sure I'm okay with them being advertised here. All sorts of sites are okay such as other forums, blogs, even sites where you want to sell products. As long as we find it to be family friendly and not push any agendas that people here might be offended by, we're all good.
Also worth noting... Same criteria, if I find a site is worthy to be listed here and if anyone is interested, the main website will soon have a "friends" page where your site can be listed. You wont be able to post anything to it but, it will be a more attractive advertisement than the forum here.
If I remember to do so, I can probably have a link back here to the person's forum topic as well.
Linking back to my site isn't necessary, though it is appreciated. I mostly offer this to help my friends.