I use the following procedure that lists space used for each database by space free per file group and space used per table.  I also have it raise an error if the number of extents remaining on the data file group starts running low.

CREATE procedure checksizes as 

-- Create the temp table for further querying 

CREATE TABLE #TableTemp( 

        acquired  datetime, 

 DatabaseName    varchar(50), 

 rec_id  int IDENTITY (1, 1), 

 table_name varchar(128), 

 nbr_of_rows int, 

 data_space decimal(15,2), 

 index_space decimal(15,2), 

 total_size decimal(15,2), 

 db_size  decimal(15,2)) 

declare @dbname varchar(25) 

declare @sql varchar(1000) 

declare dbcursor cursor for select name from master..sysdatabases where dbid >4 

EXEC sp_MSforeachdb @command1="print '?' DBCC updateusage ('?')" 

open dbcursor 

fetch next from dbcursor into @dbname 

while @@fetch_status = 0 

begin 

-- Get all tables, names, and sizes 

set @sql = 'USE '+@DBNAME+' EXEC sp_msforeachtable @command1="insert into #TableTemp(nbr_of_rows, data_space, index_space) exec sp_mstablespace ''' + '?'+''''+'",@command2="update #TableTemp set table_name = '''+'?'+''' where rec_id = (select max(rec_id)

from #TableTemp)"' 

exec (@sql) 

update #TableTemp set databasename = @dbname, acquired=(select getdate()),total_size = (data_space + index_space), db_size = (SELECT SUM(data_space + index_space) FROM #TableTemp where databasename is null) where databasename is null  

fetch next from dbcursor into @dbname 

end 

close dbcursor 

deallocate dbcursor 

insert into tablesizes SELECT * FROM #TableTemp  where  databasename + table_name + convert(varchar(12), nbr_of_rows) not in (select databasename+ table_name+  convert(varchar(12),nbr_of_rows) from tablesizes) 

DROP TABLE #TableTemp 

insert into dbsizes select getdate(), d.name, f.name, f.filename, f.size*8/1024, f.growth*8/1024, f.maxsize*8/1024, Extents = case when growth = 0 then 0 else (maxsize - size)/growth end, f.groupid,-1 from master..sysdatabases d, master..sysaltfiles f where f.dbid = d.dbid and f.dbid > 4 

declare @groupid int 

declare @extents int 

declare @filename varchar(200) 

declare @dbid int 

declare @growth int 

declare spaceused cursor for select name, dbname from dbsizes where spaceused = -1 

open spaceused 

fetch next from spaceused into @filename, @dbname 

while @@fetch_status = 0 

begin 

set @sql = 'USE '+@dbname + ' update sqlmanager..dbsizes set spaceused = (SELECT FILEPROPERTY('''+@filename+''', ''spaceused'')*8/1024) where name = '''+@filename+''' and spaceused =-1' 

exec (@sql) 

fetch next from spaceused into @filename, @dbname 

end 

close spaceused 

deallocate spaceused 

declare groupcursor cursor for select groupid, dbname , sum(extents)  

 from dbsizes  

 group by groupid, dbname, acquired  

 having sum(extents) < 4  

 and sum(spaceused) > 0 and convert(decimal (9,2),sum(spaceused))/convert(decimal (9,2),sum(size))>.9  

 and convert(varchar(10),getdate(),101)=convert(varchar(10), acquired, 101) 

open groupcursor 

fetch next from groupcursor into @groupid, @dbname, @extents 

while @@fetch_status = 0 

begin 

set @growth = (select max(growth) from dbsizes where dbname = @dbname and groupid = @groupid and size <> maxsize) 

set @sql = 'File Group '+convert(varchar(2),@groupid)+ ' on database '+@@servername+'/'+@dbname+' has '+convert(varchar(2),@extents)+' extents of '+ convert(varchar(5),@growth) + 'MB and less than 10percent  free' 

raiserror(@sql,16,1) with log 

--print @sql 

fetch next from groupcursor into @groupid, @dbname, @extents 

end 

close groupcursor 

deallocate groupcursor 

--drop table #dbtemp

GO