Great, thank you Joe. We actually went through this exercise for a ticket recurrence scheduler in our custom built help desk application. What we ended up with gives us almost infinite flexibility, but is perhaps a bit complicated. In case it helps you, here is how ours works:
Months grid with checkboxes for JAN - DEC
Days of the week grid (1) with checkboxes for SUN - SAT
Days of the week grid (2) with checkboxes for "DAY 1st", "DAY 2nd", "DAY 3rd", "DAY 4th", "DAY 5th", "DAY Last" (Day is SUN - SAT, for 42 total rows)
Days of the month grid with checkboxes for 1-31 plus "L" for Last day of the month
Specific dates grid, with date field and insertable rows
Field for "Repeat every X days"
Each of the grids/fields is dynamically shown or hidden based on the "Recurrence Method Dropdown":
Days of the Month [Shows Months, Days of Week (1), Days of Month grids]
Days of the Week [Shows Months, Days of Week (2) grids]
Periodic [Shows Months, Repeat every X days grids]
Specific Dates [Shows specific dates grid]
If you're interested in any screen shots of this, just let me know and I'll shoot you an email.