Have pop-up notifications (or a dedicated notification area) in shopping cart to alert customer of opportunities or important news. Examples:
- (Member acquisition) Non-member being prompted to purchase a membership to save on tickets
- (Member retention) Expired member (or about-to-expire member) prompted to renew
- (Upsell/Cross-sell) Promote upcoming event/exhibit w/ link to buy tickets
- (Fundraising) Reminder to donate to special fund opportunity
- (Informational) Musuem will be closed due to unforeseen maintenence, etc.