Have you used place value disks as a manipulative for building place value? My kids love them as a change from the place value blocks we frequently use.
You can order the disks from Crystal Springs books. Click on the pic above to get the ordering info.
You can use the disks in the activity I've posted below to practice adding and subtracting with regrouping.
Just click on the pic above to download.
(Please leave plenty of comments!)