The letter spacing looks a bit uneven. I would try to shorten the r and drag the d slightly to the left. And then I maybe would drag the pair r and d to the left, but only a little bit.

In the first one, the q and d counters are too big.
In the other ones, as Arno said, the r should be modified to harmonise with the curve of d.

I am not getting "data visualization" nor "interaction design" from this at all.

Would drawing the logo to suggest a graph plot help?

Do I recognize my own Houschka there Julie?

My main concern is the name itself. Is it pronounced 'squared'? If so, people may have a tough time converting the verbal name with the URL in their head.

I think with a little concentration on balancing the counters with the other letters as mentioned would help but am troubled by the fact that to me this does little to reflect either data virtualization or 'geeky/maths'.

If I had to choose a design from the 3 featured I would choose the middle version, it has a fun touch with the red but without overdoing it.

Edit: A bit of a gimicky suggestion but maybe extend the q to feature a tail, as in my example, suggesting the x and y axes of a graph?

Thank you all very much for all your responses. And yes, Nick, it is Houschka! l love it dearly. (Sort of star-struck now:)).

Regarding theme, I don't think the logo itself has to reference anything math related. The aesthetic feel of it just needs to err a bit on the left-brained side of neutral, since the clients/projects do (for now). As apposed to, say, a logo for a company specializing in tv spots for children's programming, which might want to be friendlier.

Name confusion: hasn't happened yet. People are pretty used to weird spellings, and at present url typos don't resolve to anything troublesome.

People seem to prefer the thin version, overall, even though I don't feel it has enough ink in it to scale down well. I've compromised with:

I think it solves some of the q/d counter problems. Can't decide if the "s" is a smidge too far out, though.

Maybe I'm missing something - but what's the deal with the red tip? Is it just embellishment or is there a meaning there?