dkwatts and ARJWright go in the direction of a browser add-on. There are some candidates in the Firefox arena. This would be an interesting path since we have a Mozilla based browser and the Mozilla guys seem to be targeting most mobile platforms (including S60). Perhaps that code running on Maemo 5 could be quite cross-platform?

allameswereout, syncing with an online service of your choice might be the easiest path? You could have all your devices syncing there, instead of trying to make them sync between them without Internet.