Hop Protocol is live on Arbitrum, it now bridges Arbitrum, Optimism, Polygon, xDai and Mainnet. Once CEXs start supporting L2s, you'll never need to send an expensive L1 transaction again!

Hop Protocol lets you move assets between various L2s and sidechains instantly, for relatively low fees.

It also allows withdrawing from Optimistic Rollups instantly, bypassing the 10-day slow-bridge.

Right now Hop only supports USDC and USDT on all these chains, and it also allows Dai and MATIC on a few of the chains. I imagine more assets will be added soon.

The only thing left for our L2-centric world is for CEXs to support L2s for easy on-boarding. Coinbase announced that it's in progress, so hopefully this will be ready soon!