Subversion on a stick
Subversion is one of the best version control applications. If you've never used Subverion before, then do yourself a favour and go have a look at it.
One of the things that I use Subversion for is to synchronise my documents between various computers, be it at home, at work or elsewhere. In the past I had to keep my home computer on and my internet connection active in order to access my documents repository. but now I've found a feature that I'd like to share -- you can access a Subversion repository on a portable hard disk or flash disk without having to run a Subversion server. All you'll need is a Subversion client.
The steps follow
Step 1: Download and install a Subversion client
You can use the command line client, or TortoiseSVN. The command line client is useful if you want to write batch files; TortoiseSVN is recommended for Windows users. The following steps use TortoiseSVN.
Step 2: Create a new repository
Create a folder using Windows Explorer, let's say it's called D:\Repositories\Test. This folder should be located on your portable hard disk or flash disk, because this is the part that you'll be dragging around with you. Open that folder and right click on the client area, select TortoiseSVN and then Create repository here. Choose the native file system option.
Step 3: Create a working copy
Right click on the My Documents folder (or any folder of your choosing), and select SVN Checkout from the popup menu. You should see a dialog box like the one below.
In this example, I've called the repository that I created in step 2 Test, though you may want to call it something a bit more logical like docs or MyDocs. In the URL of repository field, fill in a URL that points to the newly created repository, i.e. file:///D:/Repositories/Test. A window should pop up stating that it has completed at revision 0.
Step 4: Start using the working copy
Go to the My Documents folder (or the folder where you created the working copy) and drag some files to it. Select the new files, right click on them and from the TortoiseSVN menu, select Add. This command will mark the files for addition to the repository.

To complete the add, right on the client area and select SVN Commit. This will add all the files marked for addition to the repository and commit new versions of files already in the repository.
Step 5: Rinse and repeat
Armed with your portable hard disk and a Subversion client, you can repeat step 3 on each computer where you would like your files. And because Subversion is designed to be a version control system for concurrent software development, it works really wekk at synchronising changes between various working copies, even if a file was modified on several computers. Sweet!