Dont listen to these clowns...
If you want Google to visit you 24/7/365 like it does us you need to setup a structured site and cross link that site with several others all with a 'similar' structured pattern.
For example, on GWW, we link to our other resources, each has a similar layout/structure.
On each of our other resources, we link to GWW making sure that the GWW links get placed before the other sites in our network.
This is called a 'spider trap' a way of ensuring that a spider bounces from one of your sites, to another, constantly, as long as the spider is crawling, itll never leave our resource network
We have Google, Yahoo, MSN, Yandex and several other spiders on GWW 24/7 because of this structured linking method.
Also, make sure you have a robots.txt file in place, it will not only stop a shitload of 404 errors in your logs but, each time it gets called, you'll know you are being / have been spidered.
Regards,
Lee