The impressive pace of expansion in the ETF industry over the last several years has been well documented; continuous product development has resulted in the launch of hundreds of products each year, and there are now more than 1,400 names in the ETF lineup. But while the depth of the ETF space has increased, the industry remains quite top-heavy; a relatively small number of products accounts for the lion’s share of total assets.

Most of the largest ETFs are also among the oldest, and their impressive asset bases are perhaps more attributable to their seniority than the appeal of the underlying methodologies. In fact, impressive innovation in the industry has given investors plenty of alternatives to the “super tickers” that dominate the space.

The largest ETFs have become so popular for a reason; they generally offer cheap, liquid exposure to core asset classes. But for investors willing to dig a bit deeper, there are some potentially exciting alternatives beyond the big dogs at the top:

1. S&P 500 SPDR (SPY)

Overview: This ETF is one of three offering exposure to the S&P 500, a widely followed benchmark of large cap U.S. equities.

ETF Alternatives: Vanguard’s VOO offers exposure to the same index at a lower price point (0.06%), but the most intriguing alternative may be the Guggenheim S&P 500 Equal Weight ETF (RSP). That fund includes the exact same names as SPY, but gives an equal weighting to each component. The result of that seemingly minor difference has been huge in terms of returns: RSP outperformed SPY by more than 11% in the trailing five year period.

2. Gold SPDR (GLD)

Overview: GLD is one of four ETFs that invests in physical gold. In fact, GLD is one of the largest holders of gold bullion in the world and has about $75 billion in assets.

ETF Alternatives: For cost conscious investors, IAU should be rather appealing. That iShares fund holds the exact same asset (physical gold) but charges 0.25% instead f 0.40%. That material differential virtually guarantees that IAU will deliver better returns over the long run.

3. Vanguard Emerging Markets ETF (VWO)