Sometimes identity columns must be reseeded.  A good example is when merging data from a couple of different  data sources.  There is a DBCC command that makes this task easy.

DBCC CHECKIDENT (<table name>, RESEED, <new value>

To find what existing identity column values are, a simple query can be written off the sys.identity_columns system view.

SELECT   OBJECT_NAME(object_id) AS [Table],
         [name] AS [column],
         seed_value,
         last_value
FROM     sys.identity_columns
ORDER BY 1