Being able to search the subscriber list with "Only if Custom Field 1 equals X value" would be really handy.
This would just be a couple of small dropdowns next to the search box on top of the list on the subscribers page.
It would also be cool if you had a "make a new segment from this search" button there.
Hey there JohnP, as always, a good suggestion there. We've had a couple of requests for more sophisticated subscriber searches, so I'll keep you posted on this one. Admittedly, it's not something we'll be adding in the immediate future, but we'll certainly keep it in mind :)