I have been using Live SkyDrive and that is (was) a great way to store and share files. The only problem is that there is no desktop interface. It is a purely web-based tool.
To keep my laptop and desktop machine synched, I use SyncToy 2.0. That tool works great as long as the machines you want to keep synched are on the same network. (And because it works on the home network - it is very fast in synchronizing gigabytes worth of files).
DropBox - I don't think would work well to synchronize entire drives of data. But here are some very, very cool features that I don't think are available in any other software at this point.
1. A public folder is provided into which you can drop files and then choose to share them with anyone through a web address. (Here is a sample file shared in the public folder:http://dl.getdropbox.com/u/129620/gis_day_2006.jpg)
2. It is extremely easy to create a shared photo gallery. All you need to do is create a folder under the Photos folder and drop your images into it.
(Check out this example that I have shared: http://www.getdropbox.com/gallery/129620/1/DropBoxSamples?h=2a1e54)
3. While it might look like you are giving people access to your drive via the Public and Photos folders, what is happening in reality is that DropBox is copying your files onto their servers, and people are downloading the files from these servers.
4. Another awesome feature available is the ability to undelete files from the drop-box folder. Because the files are stored on a server, even when you delete a file on a local drive - you still have the ability to go to the web interface and undelete these files. The minute you un-delete a file - it immediately pops up into the drop box folder.
5. It is fast!. I shared a file on one of my machines and it was almost immediately available on my other machine's DropBox folder.
If my post did not sell you on DropBox - then take a look at the screencast at http://www.getdropbox.com/#. It shows you all the cool features available in DropBox.
Currently DropBox is in public Beta. You get 2gb of space with the free account.
If by the time you get this email - the beta gets closed - leave me a comment with your email address and I will send you an invite. (I got 10 invites to give away - available to all those who register).
I wonder if this app might become the next Napster - as it makes it sooo easy to share files with other users. (And I wonder if there is anything in the EULA that prohibits users from doing so).