Investing Winner has a good article about the advantages of investing in index ETFs.
The benefits of index ETFs include:
- Diversification of stocks
 - Diversification of industries
 - Reduced risk
 - Dividend income
 - Top companies in the market
 - Tax efficient
 - Low expense ratios
 
You can also find a list of all the U.S. index ETFs in the article.
Read more at InvestingWinner.com: Benefits of Investing in Index ETFs