[development] Alternative to hook_exit

[David Metzler]

I have some expensive web service calls that are causing delays in  
one of my sites.  These calls are performed using hook_exit, but my  
themers aren't bulding themes that will display content before a page  
load is complete.

Anyone have any ideas about an alternative strategy that might be  
used so that I can load some extra information without the user  
waiting for it?  Can anyone point me to some sample code?

Thanks as always,

Dave