Web Browsing previous versions and version diffs?

[Curley, John]

Hi all,
 
Two questions, related I hope.
 
Our svn repositories are accessed through the apache/http method, which 
presents the current version of the repository. Is there a way to specify a 
previous version of the repository? Perhaps through one of those ?param=value 
clauses?
 
Is there a way to see the differences between a version and the previous 
version, in the web browser?
 
Both questions at once: is there a "web" version of the repository browser?
 
Thank you,
 
John Curley, SCM Group, Wind River