Can anyone suggest a good lightweight lock for touring? Yes, I understand the security risks of a lightweight lock!

I've been using an alarmed cable lock up to now and it's been great, but unfortunately it got water into it last year and needs replacing. I'm inclined to go the same way, as the alarm function provides that little bit extra security without the weight penalty. I've read through the other threads on the alarm locks.
Weight is important to me, so that will be first priority (given a reasonable minimum level of security e.g. something with a cable/shackle at least about 5mm. Also no combination locks as they're so easy to crack). The use will be mostly for locking our two bikes and mostly just in campsites, with the very occasional city use when we stop for lunch.
Any suggestions?