Carnival of Space.It's experimental only in that it is subject to tinkering. The intent is to be able to search through sites and pages related to the Carnival of Space. Tinkering will be limited to the addition of related sites, and changes to options to limit how far the search can expand itself.
Currently, the widget searches each page has hosted the Carnival and dynamically includes pages linked from these pages. The search should not expand beyond this to the larger Internet.
I will also be adding individual sites from the carnival.
I had tried some different options initially and found some the searches went a bit astray. I'll put this down to my inexperience with Google CSE widgets.
I'll update this post if I make significant changes.
Feedback is welcome.
I've also added it to the blog's side bar for when this rolls off into the archives.
For more on Google Custom Search Engine widgets, see here.
BTW. If you are considering using this widget or creating one of your own, Google's Terms and Conditions include some "Exclusivity" terms to preserve their lock-in. If I read it correctly, they don't want to share their widgets on pages with other search engines/widgets.
Update: No longer experimental. The options that I'm using to limit searching too broadly have been working well and there appears to be no need to tinker with them anymore.