As time goes on I seem to be accumulating more and more machines - whether they be physical or virtual - which causes somewhat of a problem with my bookmarks. I use my bookmarks as a sort of knowledgebase, with solutions to problems I have encountered in the past for example.
The solution to this dillema: Foxmarks. I've had this addon for a long time now - since it was just a simple little bookmarks backup application - so I'm really impressed with how it's turned out. Basically, Foxmarks syncronises your bookmarks with their server, so that you can access your bookmarks from any machine with firefox installed. It also functions as a backup if your profile goes bad.
Recently I've started at university, so I'm using my laptop as my primary machine nowadays, along with a firefox profile on the Computer Science machines. I've also got a few virtual machines on my laptop with firefox, so the amount of profiles is getting larger by the day. This is where foxmarks really comes into its own, keeping my bookmarks current between all my installations.