iGoogle's original name was Google Personalized Homepage, back in 2005 when the service was launched. It was an extension of the Google homepage that allowed you to add gadgets, feeds and themes. The Google dashboard was a great way to keep up with the things that matter to you: news, weather, mail, calendar, bookmarks, to-do lists and more. These use cases are better served by mobile apps and browser extensions. In many ways, they replace iGoogle gadgets.
iGoogle in 2007:
iGoogle in 2012:
The last day of iGoogle:
The truth is that very few iGoogle gadgets were updated by their developers and many gadgets were broken or didn't work well. Google didn't create iGoogle gadgets for new services like Google+ or Google Keep. iGoogle tried to stay relevant by adding features like social gadgets and canvas view, but they were tied to projects like OpenSocial or Google Reader (discontinued).
Google Now is probably Google's replacement for iGoogle. While Google is the only one that can create cards, a Google Now API could change that. Google Now shows information that's likely to be relevant when you need it using various sources like: Gmail, Google Calendar, Google News, Web History, location services. Google also shows gadget-like cards for searches related to calculations, unit conversions, weather, your mail and much more.
If you still want to use a service like iGoogle, I recommend 2 personalized homepages: Netvibes and My Yahoo. They have fewer gadgets than iGoogle, but they're pretty good. My Yahoo even imports your iGoogle settings (the iGoogle settings page is still available).