The brute-force-ish but still reasonable way would be to create a new row in your single events table for every instance of the recurring event, all pointing not to the event preceding it in the series but to the first event in the series. This simplifies selecting and/or deleting all elements in a particular series, since you can select based on parent id. It also allows users to delete individual items from a series without affecting the rest of them.
This query gets you the series that starts on element 3:
SELECT * FROM events WHERE id = 3 OR parentid = 3
To get all items for this month, assuming you'd have a start date and an end date in your events table, all you'd have to do is:
SELECT * FROM events WHERE startdate >= '2008-08-01' AND enddate <= '2008-08-31'
Handling the creation/modification of series programmatically wouldn't be very difficult, but it really would depend on the feature set you want to provide and how you think it'll be used. If you want to differentiate between series and events, you could have a separate series table and a nullable series_id on your events, allowing you the freedom to muck about with individual events while still retaining control over your series.
