make: remote dependencies?

Would it be possible to have remote dependencies in a makefile?

I have a task that depends on the status of files that are downloaded
from a remote location via HTTP.  This task needs to be performed
only if one of the remote files has changed, in which case, the
first thing to do is to download these remote files.  Can make
handle this?

More generally, is there a more general way to tell make when to
consider a target to be out-of-date than by comparing the modification
dates of two files?

TIA!

kynn

-- 
NOTE: In my address everything before the first period is backwards;
and the last period, and everything after it, should be discarded.