Seriously, I’m about to give you all a million dollar idea, and I don’t care if it makes you filthy rich even if I’ll never see a dime of it. I just want this app:
I want an app that whenever the Blue Tooth on my phone detects my car’s radio, it automatically activates my Pandora app.
Tasker is the ‘go to’ app for Android automation, but its interface is not exactly the most user friendly. If the learning curve seems a bit steep, Automagic will also do the trick quite nicely…as will several other apps.
Wow thanks guys.
That app does look intimidating. I guess I’ll give it a go though.
I want a location-based alarm clock app, so that I can take a nap on the bus or the subway and have it wake me up when I get to my stop.
You can use IFTTT (.com) for that kind of thing. But GPS is necessary, so it probably won’t work on the subway…
I want a decent map app that lets me input my average speed on various types of roads to give me a more accurate ETA
I want a pony.
I want an app that runs continuously in the background and buzzes/vibrates/flashes lights when I’m about to say or do something stupid.
I want the OPPOSITE!
Keep Pandora SHUT OFF unless I specifically turn it on!
(I uninstalled Pandora because it kept coming on by itself.)
@kayaker: Too late. 
Cheap shot I know. Sorry I couldn’t resist. Not aimed at you personally.
My wanted app: One that lets me uninstall the Android & phone company built-in apps that are crapware without needing to root the damn phone to do it. And which precludes them being included as updates later.
Actually, the app would have to have an adjustable sensitivity to keep it from draining the battery.
Really?
I must drive awfully averagely. The app’s ETA is always when I arrive.
Are you a turtle or a hare?
Can I borrow it after you’re done? Some days I really need that help.
Actually you’ve got the makings of a really cool idea there.
The folks who do commentary at ball games have experts with databases speaking factoids into their headsets. Which the commentators then relay to us, making it sound like they’re channeling a Wikipedia full of personal experience and expertise.
Also consider the issues in this current thread: http://boards.straightdope.com/sdmb/showthread.php?t=811179
Combine these two ideas into an app like this:
Joe Awkward goes on a date. He’s nervous and desperate. He wears his Bluetooth headset and the whole time he’s there on his date with hapless Jane he’s also got the Siri-whatever in his phone istening to them both chit-chat.
It’s using its massive online Watson-like knowledge of human interaction to provide live real-time coaching into Joe’s ear. So he says the right things to Jane, not the dorky things. And of course the Relationship-O-Matic is learning from every person on every date it rides along on. Thousands every day.
It could even have different modes: Sensitive New Age Guy, Roid raging PUA, or Texas pickup-trucker* for the guys. Damsel in Distress, the Crazy wants your body, Librarian by day / cougar by night, red-headed cowgirl kicks your weak citified ass for the gals. And as many more as human imagination can come up with.
The possibility for profit is endless. 
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TPT: Someone who personifies the old joke:
Q: What’s Texas-style foreplay?
A: ‘Git in the truck, bitch!’
WAZE or Google Maps will do that. It will even update the ETA as you drive.
For planning, they’ll give you different ETAs depending on the time of day/traffic condition.
Tasker can also handle location-based activities like this.
If you have an iPhone, I got nothin’.
I’ve had really good luck with Google Maps. Whether I’m driving the surface streets of Boston or on the freeway, it’s always without 2-3 minutes.
We’ll call it Siri-ano?
Bravo!! Nicely done.
Or for a more Dr. Seuss vibe: “Horton gets a clue”.