Per DB: sp_helpdb
Per object: EXEC sp_spaceused 'sys_users'
For all objects in a DB: EXEC sp_MSforeachtable @command1="EXEC sp_spaceused '?'"
sp_MSforeachtable is and undocumented system proc that lets you do it easily.
I suggest dumping the output to a flat file and cleaning in excel ([Query] [Results to] [Results to file]).