I do stuff similar to TonyNo, but I only have one Away mode (two modes total: home and away).  They are used to control things like voice messages (as above).  When in Away mode I get messages and updates sent to my phone, watch, and work email.  I'm not really that worried about security.
I use a stick-a-switch to change modes.  When I leave, A1 OFF changes to away mode.  When I get home, A1 ON changes to home mode (these may or may not be the real codes - I don't want someone compromising my advanced security system 

 ).  In addition to these modes, I do have one other flag that I set.  This tells the system that I'm going to be gone for a while (travelling, for example).  This is still away mode, but the extended-away flag (device in HomeSeer) is also set to ON.  When this flag is set, I get an additional message sent to the devices/email above once a day to let me know the system is still alive (it sends me the current interior and exterior temperatures).
I have DS-10As monitoring all doors and windows (interior and exterior).  Normally, the events associated with these just get logged to a file.  But, if it's in away mode and the front door opens, there is a 5-second grace period to turn the system off (A1 ON).  If it doesn't receive that signal, it takes a picture of whoever is at the door (using a really bad camera so I don't think it's worth too much) and notifies me.
There's also a 15 second grace period when the system is changed to away mode.  A delayed HS event occurs 15 seconds after A1 OFF is received to change to away mode.
All of these are handled with really simple events or scripts in HomeSeer.
I can also control these through a very simple web page that displays on my Audreys but I only use that for testing.  The stick-a-switch is right next to the door and is normally used for control.  If I were really interested in security, I would definitely have a better setup.  I do have an RFID reader that I can use to change to home mode - but it's currently disconnected while I rig some more permanent wiring.  When this is set up, I'll disable the A1 ON (change to home mode) functionality so that the stick-a-switch can only be used to arm the system and not to disarm.