The svn list command shows you what files are in a repository directory without actually downloading the files to your local machine:

$ svn list https://svn.collab.net/repos/svn
README
branches/
clients/
tags/
trunk/

If you want a more detailed listing, pass the --verbose (-v) flag to get output like this:

$ svn list --verbose https://svn.collab.net/repos/svn
   2755 harry          1331 Jul 28 02:07 README
   2773 sally               Jul 29 15:07 branches/
   2769 sally               Jul 29 12:07 clients/
   2698 harry               Jul 24 18:07 tags/
   2785 sally               Jul 29 19:07 trunk/

The columns tell you the revision at which the file or directory was last modified, the user who modified it, the size if it is a file, the date it was last modified, and the item's name.