In the earlier years of blockchain, Bitcoin gained a reputation as "magic internet money" in part because it was simple and cheap to send small-dollar tips to random people on the internet. For most of Bitcoin's first decade, transactions that paid no transaction fee would still be mined into the mostly-empty Bitcoin blocks in a reasonable amount of time. This is no longer the case!
The Lightning Network brings back the world of simple, free, anonymous tipping and makes it instantaneous—the tip recipient can spend that money immediately, they don't need to wait for a tip to be mined into a block.
Many sites will likely spring up to make use of this tipping functionality in interesting ways. Here is a selection that we've discovered!
Links to articles, with the then-current price of Bitcoin, about the hundreds of times that Bitcoin has "died". Place flowers on these graves with Lightning payments.
LightningTip connects to LND and allows you to receive tips on your site.
While it works great, the example on Michael1011's website does not change to "thanks for your tip!" when the tip is received.
https://p2sh.info/ is a fantastic site with lots of transaction statistics gleaned from the Bitcoin blockchain. You can tip the author with Lightning on their tip page.
Sergio created an easy-to-use Bitcoin Mainnet custodial tipping wallet with Twitter login.
Tip the maintainers of the LNroute Lightning resources site.