Total Memory used by SQL Server (64 bit)
I'm not sure about a single view for memory, but you can get the information from two queries.  The first (taken from Glenn Berry's DMV queries) leverages sys.dm_os_buffer_descriptors and will show you buffer pool by database:

SELECT 
    DB_NAME(database_id) AS [Database Name]
    ,CAST(COUNT(*) * 8/1024.0 AS DECIMAL (10,2))  AS [Cached Size (MB)]
FROM sys.dm_os_buffer_descriptors WITH (NOLOCK)
WHERE database_id not in (1,3,4) -- system databases
AND database_id &lt;&gt; 32767 -- ResourceDB
GROUP BY DB_NAME(database_id)
ORDER BY [Cached Size (MB)] DESC OPTION (RECOMPILE);


The second query I put together by looking at sys.dm_os_memory_cache_entries to show me non-buffer pool information:

select 
    name
    ,sum(pages_allocated_count)/128.0 [Cache Size (MB)]
from sys.dm_os_memory_cache_entries
where pages_allocated_count &gt; 0
group by name
order by sum(pages_allocated_count) desc


There are a host of DMVs related to memory, notated by dm_os_memory_*.  You can use these to investigate how memory is used by SQL Server on a variety of levels.