Hi lhoyle
You can use ciscoworks VMS to know everything about IPSEC tunnels.. You have a module called "monitoring centre for performance" which comes with VMS package.. using this, you can have all details about site-to-site, remote site VPNs, firewall, load balancers, ssl etc...
this can give you real time and historic data.. contact your cisco partner to know more about this product...
Raj