Setting up related websites (like microsites). Hows & whys?

I really hope this isnt a stupid question...forgive me in some ways I am a newbie.. Anyway I have a main site, site A which is my ONLY money site. Good PR, loads of links, been hit a little by Panda & the deranking of BMR, but nothing serious.
I have also registered a number of domain names relating to keywords (& sections) on my website & am trying to think what to do now. I was going to set up various microsites, with my products on them, completely different written content, & a link per product back to my site A. Ive done one on weebly, was going to do wordpress, wix, blogger & any others..(suggestions please?)
But will the big G consider this sharp practice? Its a lot of work but I did one for a search term ages ago & we did really well on that term despite it not being well linked (or even a large part of our business).
I thought I could make it like a little private network, & link them (carefully) to each other & to our blog. Can anyone help with this & possible stop me making a major mistake??

Hmm sounds like you're thinking the right way.

Private site networks are going to be the Next Big Thing in SEO - mark my words.

The earlier you start building sites, the better. The more you build, the better. The better those sites are...the better.

By the way, a private network doesn't all have to link to a money site directly...think of multiple channels of 301 redirection toward the money site for those times when you want to muddy the waters in your private network (for purposes of camouflaging what you own). Also...you should always have some sites in your network that don't link to your money site at all (in any way whatsoever) but that either 1) are linked to from other sites in the network or 2) link to other sites in the network. I call these dead end sites and I put them there so my network has further variety, more branches, but doesn't clearly identify the one most important money site. In fact I may just want to use those sites for other purposes within my niche - there are a lot of possibilities for that.

Thanks Lowbrow! So it sounds like the name of the game is disguising what Im doing..maybe if I have 2 sites that use similar keywords I could just use one to link to the other one(s). So it sounds like Google take a dim view of this practice. Wonder if we could form a private members clubs for people with GOOD private networks then I could link out to other members & they could link to me & each other. Hmm. As if I havent got enough to do..