We all know mini sites are all the rage. But do they really work? In a word....no they don't. They make me feel good, but I make less money and that does not make me feel good. So if you develop, you need to develop a business, not just another site. Better yet, develop a relationship with the end user. The income will out perform PPC by as much as 10x or even more. Much more.
So I can look back over the years and without doubt, short of a full blown business, selling traffic to the end user that understands traffic and is sick of paying thru the nose for unknown quality is the way to stabilize your income and then grow it again.
It is really not uncommon to make 5x, 10x, 20x as much. And on domains with traffic that PPC can't convert, the numbers are even more substantial. Right now I am looking for an end user for a domain I have. Specialties.com that makes ZERO on ppc but has 100 daily visitors. When I turn $0/day into $10/day, I can move to the next domain. Repeat, repeat, repeat. End users are getting more sophisticated and in time this will be much more common.
Point is, when you are looking for answers, look in lots of different directions. Mini sites could work on one domain and have no results on another. Test, Test, Test. That is what allows me to write these things with a fair amount of confidence.
Have a GREAT Day!