best practices for private ports?

[Vivek Khera]

I have a few meta-ports I use to configure my base systems.  eg, I  
have a "kci-dbserver" port that just has runtime requirements for  
postgres, slony, mysql, and nullmailer.

Right now I made a subdirectory in ports called local to put them in,  
but portsnap likes to delete it regularly :-(  These are very  
specific to my server configurations so don't really make sense for  
inclusion in the main ports tree.

What is the preferred location/mechanism for having local ports?   
Ideally I'd like it to integrate with portupgrade which looks only  
in /usr/ports/* for the port files.