I was thinking that exact thing last night.. was going to look online today
The ones with the proper conturing, and higher side for the neck are better. Not all memory foam pillows are created equal.
Another idea, is try some kinesiology strapping tape. I guess it would be the same over there, you'd purchase from a physio clinic. Same with the Kinesio tapes, some are very good, and will last 3 days and others come off almost immediately. I don't know if the good brands that are available over here are over there. The best tapes are highly flexible (with a wave design on the back), are water resistant (can be out doing sports in the pouring rain all day and they stay stead fast where they were put). Bonus they come in different colours too. Can be used where ever needs be.
I use Kensio tape myself and find it invaluable.
Here's a bit of info:
http://en.wikipedia.org/wiki/Elastic_therapeutic_tape
http://www.handsonphysio.co.nz/kinesio-taping/
http://www.howstuffworks.com/kinesiology-tape.htm
I don't know if this would your back or not, but it would definitely be worth talking to your physio about it.