As a software architect I despise it when my customers tell me fixes instead of just telling me what they are having a hard time with, so I'm not going to suggest a fix. I'm going to point out that we have a serious problem with fragmentation in the smaller sites, and hope that you smart folks at Stack Exchange can figure out how to address it.
There was a feature request about a year ago to Introduce sub-communities (or “Portals”) to prevent fragmentation. There was a feature request two years before that for Stack Overflow tag-filtered subsites. Both requests were marked [status-complete] when the facebook.stackoverflow.com mini-site was announced. Another similar question: Stack Exchange: Should some communities simply be "sub-communities" of other sites? didn't get much discussion (that was in response to the proposal to split Ubuntu off of Superuser.)
But there doesn't seem to be any way to request a minisite as an alternative to community fragmentation, I am unaware of any mini-sites other than facebook.stackoverflow.com, and none of the posts requesting the use of mini-sites (for solving fragmentation, or for commercial use) has gotten an inkling of a positive answer from a @AnnaLear or @JeffAtwood.
I understand that the Facebook mini-site may be considered a total failure, but the objective there seemed to be something completely different than avoiding fragmentation of non-commercial communities. (Although perhaps it was intended to avoid the fragmentation caused by sites like mathematica.stackexchange.com and drupal.stackexchange.com?)
- How are new Stack Overflow mini-sites created? got a negative response, and @KevinMontrose went further and said that mini-sites are unlikely to ever happen for any stackexchange site other than stackoverflow.
- Are there plans for more things like facebook.stackoverflow.com? How about this feature on other Stack Exchanges? got shut as a duplicate
- Are more mini-sites coming? got little response.
- Stack Exchange network with overlapping questions goes the other way: suggesting that we allow cross posting (between the fragmented sites that are getting created because we don't have mini-sites)!
- Smart Tags: A solution for cross posting and community sorting? suggested (essentially) that tags shared between two sites automagically suggest that you post on one of the two sites (rather than randomly on one, or cross posting on both.)
But the problem of fragmentation on Area 51 is quite real. And not just for programming problems:
Joel Spolsky pointed it out on his Stack Exchange blog.
The physics folks are currently worried about the astronomy & astrophysics proposal: How can I downvote or counteract in any (democratic) sense the creation of the Astronomy and Astrophysics site? and Why wouldn't this just be part of the existing physics Stack Exchange site?.
Is a mini-site approach a solution to these Area 51 proposals? was posted in 2011 about games.
Here's another recent post on Area 51: https://area51.meta.stackexchange.com/questions/10156/duplicate-of-it-security-se (and why we need any more fragmentation of Server Fault (138 questions a day) when we already have Database Administrators, IT Security, Webmasters (totalling 65 questions a day), is absolutely beyond me.)
In the CS area we've got: Computer Science and Computational Science and Signal Processing in beta, (and in some ways competing for attention with Theoretical Computer Science's 5.4 questions/day. (And the Computer Science site took about half the [Computer Architecture] traffic from electronics.stackexchange.com.)) And proposals for Machine Learning which some people believe are going to compete with Cross Validated.
(Also, yes I'm aware of: About having a subdomain to stackoverflow and How to build my own XXXX.stackoverflow.com Q&A?, which were both, essentially requests to use the Stack Exchange infrastructure for commercial purposes. That's not what I'm talking about.)