Share with people you know.

People you don't know, not so much.

'it depends'. If you're cautious, you won't want to tie in your username with sites you run. A lot of people tend to avoid naming sites in SEO orientated areas for a few reasons, namely you could be exposing yourself to a competitor or your more edgy comments may get people digging into your sites for dirt.

To be fair there isn't really much incentive for us to share our sites between each other here.

That's true, then again, there's also that other thing we do here which is avoid self-promotion. Webmasterworld is a different critter than most forums in that regard, and I like it that way. Keeps us focused on why we're here.

If you are not making any money from your website, you can share it without any problem.