I'm trying out SQL Server 2008 Express Edition and I'm interested in trying the replication features. Is there a publicly available database to which I could set up a replication subscription?
Not that I know of.
The Publisher's SQL Server platform would need to have administrative changes made to it in order to add your SQL Server instance as a subscriber, so it is quite unlikely you will find what you are looking for.
That said, if you come across something let me know.
Cheers, John
No, but you can set up a second instance of SQL Server (Developer, Standard or Enterprise) on your same machine and do replication between the two of them, or use a second computer, or a virtual machine on your computer. For a free virtualization solution, check out VMware Server. That's great for learning things like this where you want to test how things work with multiple machines involved.
You can't use a second copy of sql server express edition as some suggested. The expres editions can't work on both ends of the replication. Express can only be a subscriber, not a publisher. You need a higher version to be the publisher.
You can however download free trial versions that do support replication if you just want to try something out.