Back in my Treo days, I used an indispensible app called TreoStar. In a nutshell, you basically enclose notes or reminders using markup in the Notes field for a specific contact. When you call the contact, the notes or reminders will show up right on the call screen just after the connection is made.
Here's a link to the product page: TreoStar
To duplicate this functionality on my Blackberry, I would have to back out to the launcher screen from the call, go to Contacts, and open the record to view notes. It works, takes longer, and if I'm not on handsfree, the callee would need to wait a few seconds of silence while I do this. Anyone know if there is an equivalent for the Blackberry?