E-Rkive will allow you to access unlimited archives at the same time.

As well as accessing your own archives, you can view and share other archives stored on a network drive as well as viewing archives stored on CD-Rom directly.

Each archive can contain messages from any Outlook store (ie: Exchange Mailboxes, PST Files and Public folders). As long as the messages are a "MailItems", they can be archived and will be stored in a set of folders that represent the exact location they were archived from.

NOTE: The more archives that you link will impact on the time E-Rkive will take to open.