Group By partial string

Give this concept a try:

DECLARE @forumTable TABLE (names VARCHAR(100))
INSERT INTO @forumTable (names)
VALUES  
('Joe'),       
('John;Robert;Doug'),       
('Barry;Robert'),       
('Doug'),       
('Robert;Doug;Joe;John')   
DECLARE @loopTable TABLE (names VARCHAR(100))
INSERT INTO @loopTable (names)
SELECT * FROM @forumTable
   
DECLARE @thisName VARCHAR(100)
DECLARE @names TABLE (name VARCHAR(100))
WHILE (SELECT COUNT(*) FROM @loopTable) > 0
BEGIN
 SET @thisName = (SELECT TOP 1 names FROM @loopTable)
 WHILE CHARINDEX(';', @thisName) > 0
 BEGIN
  IF NOT EXISTS (SELECT 'x' FROM @names WHERE name = LEFT(@thisName,CHARINDEX(';',@thisName)-1))
  BEGIN
   INSERT INTO @names (name) VALUES (LEFT(@thisName,CHARINDEX(';',@thisName)-1))
  END
  SET @thisName = RIGHT(@thisName,LEN(@thisName)-CHARINDEX(';',@thisName))
 END
 IF NOT EXISTS (SELECT 'x' FROM @names WHERE name = @thisName)
 BEGIN
  INSERT INTO @names (name) VALUES (@thisName)
 END
 DELETE FROM @loopTable WHERE names = (SELECT TOP 1 names FROM @loopTable)
END

SELECT name, COUNT(*) 
  FROM @names
    INNER JOIN @forumTable 
        ON names LIKE '%'+name+'%'
 GROUP BY name

You can, of course, use temp tables, or actual tables if you'd prefer. It's much easier to test (for me at least) using table variables.