Possible to use SQL to sort by date but put null dates at the back of the results set?

Here's a solution using only standard SQL, not ISNULL(). That function is not standard SQL, and may not work on other brands of RDBMS.

SELECT * FROM myTable
WHERE ...
ORDER BY CASE WHEN myDate IS NULL THEN 1 ELSE 0 END, myDate;

SELECT * FROM myTable
WHERE ...
ORDER BY ISNULL(myDate), myDate

SELECT foo, bar, due_date FROM tablename
ORDER BY CASE ISNULL(due_date, 0)
WHEN 0 THEN 1 ELSE 0 END, due_date

So you have 2 order by clauses. The first puts all non-nulls in front, then sorts by due date after that