[update 2013-02-26]: you may try freeware
HarePoint Workflow Scheduler, which is much better.
The open source project here is mainly for learning purpose.
SharePoint 2010 workflow timer, which can schedule site workflows and list workflows. Sub sites supported. Upgrading from previous version is not supported.
SharePoint 2010 only.
During the installing, the objects below will be created for the specified site collection:
List to store the workflow relevant information.
List to store history data and debugging data.
Links library to store the links of the timer job's maintenance pages.
If this document library doesn't exist, then it will be created to store the maintenance page.
6. 5 timer jobs for Minutes, Hourly, Daily, Weekly and Monthly timer.
7. "EF WorkflowTimer Admin" link under "Site Settings" -> "Site Collection Administration"
8. If cannot activate the feature, please follow http://efworkflowtimer.codeplex.com/discussions/361266
More screenshots are