I took advantage of the low on-chain fees yesterday to (allegedly) transfer the minimum deposit (5 mBTC) and open an account at Nitro Betting.
It's a traditional sportsbook that also seems to have various games of chance in a casino. So far, I've only put down two small bets (2k sat minimum) on Denver winning tonight and NY winning tomorrow. I strongly debated putting money on Cleveland and Dallas last night, which would have paid off.
They have parlays and survivor pools that might be fun to play around with in the future.