First up, iGoogle, from Google, of course. You need it your Google ID & password. Some things to note - you can create multiple tabs to display different groups of content, you can choose a different theme for each tab.

Next NetVibes, again you can create multiple tabs, choose a custom color theme, although the same theme will apply to all your tabs.

Last but not least, My Yahoo, you can use the same Yahoo Id you use for your email for Flickr to sign in an create the page. You can create multiple tabs to display different groups of content, you can choose a different theme for each tab.

They all work a bit differently and have different widgets. It really comes down to which one you prefer to use. Once you get it set up though, it can be a great time saver and information management tool.