Thermopane Windows usually have a metal strip separating the panes of glass. Often the date of manufacture is stamped on it. This will give the year of construction -- or renovation of the home.
Electrical Panels and Meters also carry dates. The New Home Warrantly sticker was placed on the electrical panel and carried the date of possession of the house. Most electrical meters also carry dates -- the date of manufacture of the meter can help in establishing the age of the house or the date of an electrical upgrade. Sometimes an electrical inspection certificate is attached to the panel. This too will give the date of construction.
Gas Lines and Meters carry dates too. Many meters have dates stamped on them and often the installer of the gas line leaves a tag certifying the test on the line when it was installed.
Furnaces usually have a date code incorporated in the serial number, sometimes the model number. Each manufacturer uses a different method so this may not be that obvious to a layman. A professional home inspector, on the other hand, can refer to technical reference books to establish the date of this type of equipment.
Hot water tanks also have a date code included in the serial number, but not always. Some makes mask the date and then only a professional home inspector will be able to tell the date by consulting the manufacturer's technical manual.
Boilers usually carry a date. Most of the Allied Engineering boilers use in our area have the date written on the lower right side of the plate supporting the burners. Others have the date in the serial number. Others have a consumer protection number and one has to call the manufacturer.
Plumbing fixtures such as toilets often have the date of manufacture stamped on the udnerside of the lid or inside the tank.
Aluminum wiring was used from about 1965 (mostly in the 70's) to about 1978. The presence of aluminum wiring indicates the decade of construction.
Knob and tube wiring was superceded by conventional wiring in the late 1940's. However, it wasn't until the end of the 50's that wiring included a ground wire. Knob and tube wiring indicates 1940's or earlier construction. Two-prong outlets indicate 1950's construction.
Ground fault mechanisms have evolved too. Before 1975 GFI protection in bathrooms was provided by an isolation transformer in a large box behind a two-prong outlet. This is why you see a large cover plate. In 1975 it became mandatory to provide GFCI protection for outdoor receptacles and the bathroom could be on the same circuit. Both circuits were connected to a ground fault breaker on the electrical panel and the isolation was deleted. Since 1987 the outside circuits must be on their own circuit and cannot be linked to the bathrooms. From this time forward we see the familiar three-prong outlets with the GFI incoporated (re-set / test buttons).
Electrical service entrance wiring might be useful in some rare cases. Before 1987 #6 R90 Cu was rated at 70 amps. After 1987 the rating was reduced to 65 amps and it could no longer be used on 70 amp service. Today's standard is 100 amp service and many homes have upgraded. Any home with less than 100 amps would attract a recommendation to upgrade anyway and it wouldn't be useful to date the house on the size of the wire -- it wouldn't be significant in the scheme of things.
Plumbing waste pipes were usually cast iron until the mid-50's when it changes to copper. When copper prices rose in the late 60's, plastic became the preferred waste plumbing material.
Plumbing water/heating distribution lines are other indicators. Galvanized lines were likely used before 1950. They have mostly worn out and have been replaced with copper or plastic. Polybutylene (grey) is the most commonly found. It was used in the late 70's and up to about 1996 when it was replaced with PEX.
Plaster was widely used on walls and ceilings before 1960 and drywall since.
Sub-flooring and roof sheathing was often planks up to the early 60's and plywood from then until the early 80's when OSB replaced it.
Please be reminded these are just hints which may be helpful only in some circumstances. You should always use a professional home inspector to check out the property for you prior to making the final decision to purchase a property.