SCOM Alert Description

A list of custom properties for alert description and notification:
For event Rules:

EventDisplayNumber (Event ID): $Data/EventDisplayNumber$ EventDescription (Description): $Data/EventDescription$ Publisher Name (Event Source): $Data/PublisherName$
EventCategory: $Data/EventCategory$ LoggingComputer: $Data/LoggingComputer$
EventLevel: $Data/EventLevel$
Channel: $Data/Channel$ UserName: $Data/UserName$
EventNumber: $Data/EventNumber$

For event Monitors:

EventDisplayNumber (Event ID): $Data/Context/EventDisplayNumber$ EventDescription (Description): $Data/Context/EventDescription$ Publisher Name (Event Source): $Data/Context/PublisherName$
EventCategory: $Data/Context/EventCategory$ LoggingComputer: $Data/Context/LoggingComputer$
EventLevel: $Data/Context/EventLevel$
Channel: $Data/Context/Channel$ UserName: $Data/Context/UserName$
EventNumber: $Data/Context/EventNumber$

The full list here:
http://blogs.technet.com/kevinholman/archive/2007/12/12/adding-custom-information-to-alert-descriptions-and-notifications.aspx

SCOM Rule based notifications

Whilst SCOM can handle a more granular rule/monitor based notification, it currently cannot be done through the UI. Deploy the following code to acomplish that:
http://blogs.msdn.com/jakuboleksy/archive/2007/01/18/notification-subscriptions.aspx
or a powershell veriosn of the same:
http://code4ward.net/cs2/blogs/code4ward/archive/2007/09/19/set-notificationforalert.aspx

SCOM Script Maintenance Mode

Powershell scripts to schedule a computer, or a group to maintenance mode:
http://systemcenterforum.org/wp-content/uploads/CmdSchedMaint.zip