Chirp is a free Chrome extension which allows you to send links to nearby iOS/ Android devices using sound.
All you have to do is visit the page of interest, and either click the Chirp button on your address bar to send the link, or right-click an element on the page (a picture, say) and click Chirp to send only that.
The extension then encodes the data in audio form, plays it as a sound (something like R2-D2, only faster), and any nearby iOS or Android device running Chirp in the foreground should pick it up.
That "should" is maybe questionable, as it depends on the volume of your device, the distance they are away, the sensitivity of their microphone and the amount of background noise.
Still, it worked for us, and as long as the volume is high we didn't have any issues with minor background noise.