Hei!
I've found the superb service at http://openkeyval.org for storing simple key value from any webapps. From the docs it seems like it allows 64kBytes of data, put from what I see it's only possible to store 512 bytes.
See the example below (press load to load data from my key, and save to store back into key)
http://jsfiddle.net/larsi/h8Mbg/
Any ideas what might be causing the limit?
Regards Lars Erik