Just like the Curve stablecoin pools, where holders of stablecoins can provide liquidity and earn fees on swaps, the Balancer Labs pool will allow ERC-20 token holders to invest in existing liquidity pools of up to 8 coins, or make their own custom coin pools and earn fees.
"Balancer allows pools with up to 8 tokens, with any custom %-distribution of value for each of them. Anyone can now create their own self-balancing index fund, or invest in someone else鈥檚."
Balance Labs has raised 3 million USD and from what I have read on their Discord the protocol should be launching very soon.
If you have a Metamask wallet, you can test the beta version on the Kovan testnet https://kovan.pools.balancer.exchange/