Alot of the SP Services don't actually run as Windows services but rather inside of the timer service.
So, here is the list of things I think need to be monitored in order of importance
World Wide Web Publishing Service (without this, you got nothing)
SharePoint 2010 Timer - As explained above, some other services depends heavily on this guy.
SharePoint Server Search 14 and or SharePoint Foundation Search V4 depending on what type of search you're using.
Forefront Identity Manager Service and Forefront Identity Manager Synchronization Service.. If these guys go down, your profile sync will stop..
The rest of the services (such as MMS, BDC etc..) dont run as actual windows services but rather as WCF endpoints . To find these, check the nodes in your IIS Menu and you'll find them.
Hope this helps.