Once Amélie has been designed and built, other possibilities will be considered.

Until then, a few rough notes:

• Central heating controller
  This could be made extremely easily. Those wall-mounted thermostats are digital, the thermoswitch is either 'on' or 'off', so interfacing one (or more) of these shouldn't present any great challenge.
  The motor, boiler, and valves (if required) can be switched by way of relays.
   
  
• Burglar alarm
  This also is not anticipated to be overly problematic; reed switches can be daisy-chained and fed into an input, either normally-open or normally-closed, or both? Tamper circuits, intelligent or multiple siren control is possible.
  Also possible is an alarm that 'memorises' the state of switches when switched to alarm mode; so doors/windows which should be closed but are not can be omitted from the alarm scanning.
  Or, to be even smarter, if things that should be closed are not, it can enter fault mode. If you then take it to 'off' and back to 'alarm' then it'll force those sensors to be omitted.
   
  
• Washing machine controller
  The older/simpler washing machines (i.e. not the sort that claim to weigh your wash) are simple on/off systems; the water fill sensor is on or off. The motor is running or not. In the washing machine, a timed mechanical contraption makes everything work at the right times.
  This lends itself to microprocessor control using relays.

• The central heating and washing machine systems switch mains voltages, so you'll have to be very careful here.
  Additionally, the central heating would need an effective failsafe so the boiler doesn't get switched on forever, or even worse if the boiler is fired up but the pump remains off.
  In the case of the washing machine, remember than most heating elements draw 2kW or so, thus it will need a powerful relay. I have had a relay 'stick' on me before when switching heavy current loads, so it might be worth adding additional monitoring to not empty the drum if the heater is on, but instead sound a siren (or a crowbar circuit to blow the main fuse).
   
  
• If you are switching relays with Amélie's power source, you'll need effective spike protection. Having said that, many relays are 12V while Amélie is 5V, so it is generally expected that one main power supply would provide power to both systems.

Another idea is the use of the upper 1024 bytes of RAM as a place to soft-load code. The code could be uploaded using X-modem, for example, and then execution would begin at &0400...
At this time, thoughts have been made for a basic X-modem implemetation where each 128 byte block will be copied into place without checking the checksum. Then a calculation will be performed and the value of the LAST byte checked. If the two match, the code will be executed. This method isn't foolproof, but it will remove the need for either proper checksum calculation code or a lookup table (remember the X-modem checksum is 16bit).