Send a fan letter to someone who isn't famous

People tend to enjoy having their work praised by a stranger, especially when it's not a common occurrence. Sending a fan letter is one tried-and-tested way to acknowledge someone's work. This has some potential pitfalls, but these can be mitigated:

 

1) It could seem patronizing. To avoid this, pick someone whose work you genuinely enjoy (e.g. the chef at the hole-in-the-wall taco stand whose food makes you drool noisily).

2) It could seem creepy. Sending the letter to the organization/general location (e.g. sending an e-mail to the address of the local bowling team or leaving a note in a place where your favorite graffiti artist is known to work) will help. Also, although this should be obvious, avoid saying anything remotely sexual or stalker-ish.

Effort involved: infinitesimal. Crafting a note is easy, and could be as simple as leaving a "Nice snowman!" note in a mailbox.


Image from http://www.life360.com/blog/10-awesome-snowmen/