Google Suggest significantly speeds up the search process and certainly makes search experience much better. But besides the core utility of Google Suggest, it also has many other uses.

For example, according to Google:

The fact that it is fully automated and works without any human involvement makes keyword suggestions on Google autocomplete an excellent source of keyword ideas. Quite often the new topics that are gaining popularity on Google will start showing up in the autocomplete even before appearing in trending searches on Google Trends.

There are many keyword research tools that scrape Google Suggest to get keywords. However, the best keyword suggestion tool on Google by far is Keyword Tool, and you can test it for yourself right now.