Recently I created about 60 tables in a single database, but realized I forgot a column when building the schemas. Instead of manually entering the ALTER TABLE statement for each and every table, I found the following SQL snippet to generate the statement for each table:

SELECT 'ALTER TABLE ' + QUOTENAME(ss.name) + '.' + QUOTENAME(st.name) + ' ADD [<New Column Name>] <Column Type> NULL;'
FROM sys.tables st
INNER JOIN sys.schemas ss on st.[schema_id] = ss.[schema_id]
WHERE st.is_ms_shipped = 0
AND NOT EXISTS (
    SELECT 1
    FROM sys.columns sc
    WHERE sc.[object_id] = st.[object_id]
    AND sc.name = 'report_date'
);

Then it's simply a matter of copying and pasting the results into a new query and executing!