The Google web site now includes a page offering one-stop access to all of Google's downloadable software.
On the Google Software Downloads you can page read about and then download each app (five are listed) one at a time or utilize a button which will download all five apps with a single click.
On the page you'll find:
+ Google Toolbar
+ Google Desktop Search
+ Picasa Photo Organizer
+ Google Deskbar
+ Gmail Notifier (BETA)
You'll also find a link to the Keyhole site.