Paul,
I don't think the temp querydef would help here--the issue with that was that the sql text alone was increasing the size (in my case, now that I recall, it was looping record by record, so a million sql statments at possibly 1k per pop will do it).
I'm not sure if there's a workaround for the cases where the importing causes this. Are you importing directly to the destination table? If you're using a temp table, this would be the problem--you delete the records but they're not really 'deleted'. I think regular compaction is the only way here.
Jenn,
It sounds like you have a similar issue as Paul, the Make Table query is increasing the size of the db, but deleting that table and re-running the query won't reduce the size, again compaction is the only way.
Basically, the size of the db wont shrink on it's own, so if you add records or tables and then delete them, you won't see the reduction until you compact.
--Jim