Validus, yes there is a simple way to do that :-)
RewriteEngine on
RewriteCond %{REMOTE_USER} ^Paul$
RewriteRule .* /path/to/index.html
RewriteCond %{REMOTE_USER} ^Jim$
RewriteRule .*
http://www.yahoo.com
You can also use the user in the path to redirect to, for eg if you wanted to send Paul to: site.com/members/Paul/
RewriteCond %{REMOTE_USER} ^Paul$
RewriteRule .* /path/to/members/%{REMOTE_USER}/
hope that helps!
Richard.