It would be nice if some added functionality was available when creating workflows. Seems the only time a regular workflow can kick off is if the record is created or edited. This is not good for "quasi" time-based workflows (i.e. send a notification when the date in a certain field reaches a pre-determined date - 2 days before X). It would be nice if a workflow rule could be evaluated at some specified time interval (i.e every 24 hours or every Monday at 7am, etc). It would be really nice if workflows could be evaluated "on the fly" (according to some real-time criteria).

Time-based workflows don't really solve this since once a time-base workflow is triggered, the record is locked and can't be altered until the workflow has run it's course. This is a headache for things like lead escalations (i.e. if a lead is locked into a workflow, it can't be converted until the workflow runs its course)