If you know the server and the table name, but not which database it is in, run this:
EXEC
Oddly, you need to run it in Query Analyzer, not SQL Management Studio as the latter will start to execute it, but will through an error before it completes (at least in my situation it does...could be the number of databases).
sp_MSForEachDB "SELECT name AS '?' FROM [?]..sysobjects where name = 'TableName'"