Younity offers an unusual twist on file synchronisation/cloud computing -- the service allows you to bring all of your online file and image storage accounts under the one umbrella. While not storing files online, it means you can access any of your files on any of your devices -- mobile, PC or tablet. Great for accessing music libraries, movies, all of your documents, etc. If a particular file resides only a PC, users will need to take care that the PC in question is on, or the file will be unavailable.
Google Docs, aka GDrive
In a small but significant move, Google Docs now allows users to upload folder structures as well as files. Recently they opened Docs to uploads of any kind of file. This helps Docs move a bit closer to the fabled GDrive. Still not as functional as DropBox with its efficient and seamless file synching, but an increasingly viable place to store and work with personal or business files. Google seems to be putting a lot of resources into its cloud products, so watch out for ever more fully featured iterations of Docs, Gmail and their music storage service.
Take DropBox to the Next Level
If you are a cloud power user and you have hit the 100Gb DropBox storage ceiling, then you might be looking elsewhere (such as Rackspace) for online storage/synching options. But wait — DropBox will allow you to break right through that ceiling! Unfortunately, their 350Gb Teams option seems to be oriented more towards small/medium sized businesses than individual users. At $795 per year (5 user license), $2.20 per Gb seems quite steep. Rackspace clocks in at around $1.80 per Gb per year, and their rates are calculated on the amount actually stored, not on the maximum storage amount. That said, DropBox still has the best and simplest synching and interface (and has just passed 100,000,000 users).