It's so cool looking at things up close.
With the Carson 60x-120x pocket microscope, you can see each individual pixel on the screen of your phone, or gross dust mites, and with the Nikon 8x25 pocket binoculars, you can see musicians onstage or animals while you're out for a walk (there are better binoculars out there, but the best binoculars are the ones you have with you, so I put a huge premium on ones that fit in a coat pocket and I keep these in my Advice: Car bin for longer trips).
Nikon Trailblazer 8x25 ATB Waterproof Black Binoculars
(note: you may be tempted to get the 10x ones instead, but keep in mind that as you get greater magnification, you're decreasing the amount of area you can see and the amount of light that the lenses let in)
(I've recently ordered another pocket microscope, also made by Carson, that has a clip for attaching to your phone for pictures and more social/collaborative investigation — It's 100x-250x, so I'm expecting it to be notably more fiddly, but the other options (mostly with cables or wifi) seemed to really be exaggerating their levels of magnification)
See also: Capturing moments for more info on using your phone with binoculars to display and capture images via “digiscoping”