as far as i can tell, i think that google uses early 2007 pics for more developed areas, which is about as accurate as you can find for free.
unless youre local government agency has some published...like the dallas/ ft.worth area does here, but even then they are almost identical to google's
"Don't worry about the world coming to an end today. It's already tomorrow in Australia."
---Charles Schulz
"Beer is living proof that God loves us and wants us to be happy."
---Benjamin Franklin
If all you need are photos, rather than scaled photos suitable for mapping, the Google Earth and the other free sources are you best bet BUT,
If you need accurate maps, then Fattdad's suggestion is "best", but also most expensive. It also requires field survey work, preferably pre-marking, for really reliable mapping.
If you local jurisdiction(s) have a good Geographic Information System (GIS) that may be adequate and probably least expensive.
For historical photos and "oblique" photos you may find these at your local library or University.
For simpler maps, suitable for preliminary work in the U.S., the National Geographic Society publishes Quadrangle maps on CD for reasonable cost.
Thanks for the responses. I've used terraserver many times in the past. I'll try the local GIS route, thanks for the brain jog. Most of my work is in low population and rural areas, tough sometimes to get good aerials off the net.
In rural areas, your best source may be the USGS National Aerial Photography Program. These are used by the Agriculture Department for crop measurement, and are very accurate.
In rural areas, having the site flown can be done relatively inexpensively. Especially if you want to use it for your topos. Quite a few firms out there offer these services and will work with a local surveyor who sets the control.
I've had surprising luck actually contacting small airfields and asking if ppl do this type of stuff. I've found 3 different guys who do professional aerials as a side job by this method, and the prices are reasonable for distances reasonably close to the airfield.