.Zip and .rar files should be recognized by ArcCatalog so user can zip and unzip from within ArcCatalog rather than unzipping first so the files may be viewed in ArcCatalog.
You can add file types using the ArcCatalog application options (files tab), including zip. If you do so, they appear in ArcCatalog and ArcMap's Catalog window. If you double click the zip file, it will open using the windows file association for .zip (Winzip for example).
This doesn't exactly do what you want but it is close. I think it would be neat if ArcCatalog could look inside zipfiles and access their contents read-only directly.
