Here is a handy script to check sql server blocking.
SELECT p.spid
, DB_NAME(p.dbid) AS [DB Name]
, p.program_name
, SUSER_SNAME(p.sid) AS [Login Name]
, p.hostname
, p.cmd
, p.status
, p.blocked
, login_time
, last_batch
, p.spid
FROM master..sysprocesses p
WHERE p.blocked <> 0
AND EXISTS ( SELECT 1
FROM master..sysprocesses p2
WHERE p2.blocked = p.spid )
I got it from a dba for arabic dating site. They have millions of users and all pages are served from database, this can become very useful to monitor blocking.