How to determine the amount of free space per db ?

The question I have is really basic : What is the best way to determine the amount of free space
or used space per database ?

I want to determine these numbers remotely, e.g. to build reports. I know I could use the strored
procedure sp_spaceused, but that will give me the numbers for both the data as well as the log
segments of the database. What I would like to know, is there a better way to determine the
numbers for all databases, per log and data segment ?