There is a sand additive that you can add to your driveway sealer that can make it less slippery. It's usually sold in bags and can be found near the driveway sealers and stains in your local home center. However, if your driveway is very steep, we would suggest a tar and chip driveway.
In this application, the aggregate is mixed in with the tar to create a rough surface. You will often see this in northern climates, especially where driveways are small and steep. If you're having the driveway resealed by a pro, remember to ask for the tar and chip driveway by name. Unless they do this type of driveway on a regular basis, they may not be familiar with it. What ever you do, don't use a straight sealer, because the driveway will be slippery all over again.