Dan - I empathize with you - having panic attacks for that many years must be incredibly daunting and disruptive to the quality of your life.  You don;t say how many years you have been in therapy and I wonder if during that therapy times you have done any "challenges" or behavior modification attempts since at the heart of panic attacks is the idea that if the situations that provoke it can be re-created so you can, in a safe place (therapist's office) deal with them - you may begin to be able to avert the heightened response.

I'd also recommend learning some calming techniques (breathing, meditation) so again, you can use these tools and behaviors right at the beginning of an attack.  I'm not to fond of buying TV infmmercial products, though once in awhile there are some that have merit.  Tapes that talk you through anxiety and even music therapy can certainly help though.  Finally, depending on how long you've been with this therapist, you may need to assess if you are making any progress, but that also means you do the homework you are assigned.