There may be better ways to do this, but suppose you want to get Aegir to provision a lot of sites, maybe from a list you've got in CSV file, then you can now use Feeds!
The Aegir feeds module exposes the key details to feeds, so that it can create site nodes. Whip yourself up a feed importer preset with the source of your choice, create site nodes and map your values to the servers and install profile that you want Aegir to use. Simples.
Aegir is designed around custom node types, and it is a total pain...
