Google Labs
Google is always coming up with new programs and additions to its site. To see what they are working on, you can go to labs.google.com and click on something you want to see. Please be advised that the new projects are in BETA, meaning that they are being tested and are not completely ready for release or have not been fully intergrated into their services. BETA projects may have bugs or give errors, but generally these problems are small and the services can be used quite well.
The Microsoft Network (MSN) also have a technology playground which showcases Microsoft’s latest projects. You can visit the MSN Sandbox at sandbox.msn.com. You may notice some of their projects are quite similar to Google’s. Take a look and let us know what you think by leaving a comment to this post.
UPDATE: Yahoo! also has such a page, with some original and innovative ideas. Simply go to next.yahoo.com and have a look around. Most of the new technologies on Yahoo! Next are online at the time of writing so you won’t have to install anything.