Here are some suggestions (mostly inspired by song titles) you can use when brainstorming what to build!
Take Me To the Riot: Shows you nearby trending venues and tells you why they're trending.
Bumpy Ride: Analyzes your last year of check-ins, tells you how many times a week you went to the gym, how many days you spent at airports, how often you get a haircut, how many meals you ate out, etc.
Your Ex-Lover Is Dead: Warns you if you're within 100 meters of an ex.
Don’t Stop Believing: Tells you the code for Don’t Stop Believing when you check in to a Karaoke bar.
Bumpy Ride: Gives you wikipedia stats about the roller coaster you checked in to
Konichiwa Bitches: When you check-in to an airport, post your itinerary (JFK ✈ SFO ✈ NRT)
Be Mine!: "Buy" your favorite venues and earn rent when other players check-in there.
Call Your Girlfriend: Checking in after 11pm? Text your girlfriend to tell her you’ll be home late.
Hang With Me: If you have friends checked in at home within a mile, message them and tell them to come hang out with you.
U Should Know Better: Alerts you if you've checked in to a place that one of your friends dislikes
Stars 4-Ever: Checked in to an outdoor venue after night? Give some astrological pointers.
Take the Scenic Route: Show the different length trails you could take at a state park/hiking trail
Go the f# to sleep: when you check in late when you really shouldn’t.
Fourduino: A standardized way to push checkins to Arduino devices
Don’t be late: A tie-in to your calendar. When you checkin somewhere but have something coming up in your calendar: “You gotta leave in 10 minutes to make it on time to 1:1 with harryh”
Rap Genius: Displays rap lyrics and a link to the song that reference the location I just checked in to. IE, when I visit Jacob the Jeweler, I get “I'm frozen thanks the Jacob the Jeweler.” From "Thoia Thoing" by R. Kelly
Read me!: Connects to your Goodreads account and whenever you check in to a bookstore or library, Goodreads sends back a suggestion from either your to-read list, or one of their ‘smart’ suggestions based on your reading history.
Don’t Make The Same Mistake I Did: Tips pop up when you check into a place, either telling you what NOT to do/order/etc or what definitely to do/order/etc (could tie in with “people talk about”)
Look up!: Tells you what flights are overhead when you check-in.