What is Big Deal Alert in Salesforce?
Your organization can use alerts that automatically send an email
notification for opportunities with large amounts. Customize this alert
to send an email when an opportunity reaches a threshold. Your threshold
consists of an opportunity amount and probability. For example, you may
want to send an email to your team that an opportunity of $500,000 has
reached a probability of 90%.
for documentation please refer the line "https://help.salesforce.com/HTViewHelpDoc?id=activating_big_deal_alerts.htm&language=en_US"
Steps to Create Big Deal Alert.
Go to Setup-->Customize-->Opportunities
