Task scheduler for SQL Server Express
You can check out the Standalone SQL Agent open source project.  It uses the native SQL Agent tables and procedures (which still exist in SQL Express) to store the jobs replacing the SQL Agent itself.  The engine is pretty well done for T/SQL and Dos commands.  Things like SSIS, etc aren't done yet.  Also the editor is only about 1/2 done, but the engine to run the jobs is the important part.