May we make a recommendation? This is where Next points you to something that isn't ours, but is worth your time.
Get out and volunteer. Especially this summer. When it's nice outside.
The City of Denver has a really great section on its website for a long list of opportunities that are available in the city.
You can clean up graffiti. Adopt an area to beautify (there are a few specific parts of the city that need some TLC). You can pick up trash. The city will even give you supplies to volunteer - including orange vests, shovels, trash bags, rakes, you name it.
It's a good way to make a difference in your community. And the City of Denver makes it pretty easy to sign up as a group - or as an individual.
All of the information can be found here.