If you've never used an Android phone and are perhaps thinking on switching to a Galaxy Nexus, running Android's latest iteration; Ice Cream Sandwich, you will probably want to try it out first. While visiting a phone shop is the obvious option, if they don't have it in stock or there isn't a retailer nearby, you have no other options.
Verizon Wireless, a major US phone network, has launched a 'Galaxy Nexus simulator' which lets you demo the Galaxy Nexus from the comfort of your own home. You simply choose what you want to do from the left hand menu and on screen instructions will guide you. This will be especially useful for users who have switched from other mobile OSs such as iOS or Windows Phone 7.
However for anyone who has owned an Android phone for a while, it won't be too useful. Most of the tasks it can show you how to do are fairly basic functions of the phone, but it does show how simple Ice Cream Sandwich is to use over previous versions of Android.
One final thing to note, this is the Verizon Galaxy Nexus so a few things won't be identical to a non-4G Galaxy Nexus.