If you're looking for a way to add commenting to an otherwise static page, the Google Sidewiki element gives you an easy and simple way to collect and display comments about a page. One of the new and exciting features of the Sidewiki element is that it allows visitors to leave a comment even if they do not have Sidewiki or Google Toolbar installed. Like all Sidewiki entries, the comments in the element will be ranked to show the most useful items more prominently.
The Google Checkout element allows you to quickly and easily create an online store using a spreadsheet. Once you have a Google Checkout merchant account, you just have to add details for each item you're selling into a Google Spreadsheet, then use the wizard and copy/paste the code into your website. The element is compatible with Blogger, Google Sites, iGoogle, and personal websites where HTML can be modified, but doesn't require any programming skills or experience. In fact, you can get your first online store up and running in under five minutes.
Virtual Keyboard element
Google Web Elements are great for folks who don't have much time or experience. However, even for advanced developers, elements are a great starting point, as most are backed by an underlying API to give you even more control over the content or look and feel. Take a look at all of the elements at http://www.google.com/webelements and stop by our help forum if you have any questions.