A tool that will create customer segmented lists using the following criteria

Spend for a period
Purchased X Product/s
Purchased in X Category/s
Cart Value
AOV less and more than
Billing address / country / state
Shipping address / country / state
Lifetime value greater / less than
Average Item Value greater / less than

Split by Month
Split by Week
Split by Day of Week
Split by Time of day

Never need to leak business intelligence to a SAAS again to get this valuable information. Keep it on your site.