[Q] Web 2.0's linking to multiple sites

I was trying to find some information on this, but
was not able to find an answer to my question, so
here it is.

If you have multiple sites around the same niche,
is it a good idea to link to them, from the same web
2.0 site, from within different articles?

I find it unnecessary to make multiple web 2.0's, let's
say on weebly, for the same niche just to link to the
different websites I have.

Is anyone doing this?