New iPhone app Assemble has one simple purpose, and manages to do it well. It lets you send out your location to a group of friends (or just contacts), along with a personalized message with any special instructions. In turn, they can use the app to navigate directly to you.
Instead of using SMS messages or e-mail, Assemble wisely makes use of Apple's push notification service. This is handy for your cheapskate friends who aren't on a messaging plan, but more importantly, clicking "view" on that message jumps them to a Google map of your location. There they can grab directions.
The one caveat here--and it's a big one, is that whomever you're sending your alerts to also needs to be a registered Assemble user with the app installed. Which means they also need iPhones with push notifications turned on. I don't know about your friends and family, but for mine that seems like a tall order.
Assuming your buddies do have an iPhone, and don't mind using a proprietary messaging system, it's a piece of cake. Advanced users can also set a location invitation to expire after a certain amount of time. This means that if someone opens your invite later on, and it's past the time slot you set, it simply tells them you're not there.
There is one big tweak on the way to make Assemble a little easier to use. The next version will be making use of Bump, the popular content and contact swapping tool. That will let people add others as contacts to the app without having to stand there and swap information. In the video below you can see how it will work. For now, it's been taken out for Bump to get its servers ready.
It's worth noting there are a handful of other apps that share these basic friend-finding and navigation features. Most notably Zhiing, which is not only cross-platform, but also includes an in-box to manage friend invites, and spoken turn-by-turn directions. Assemble also faces competition from apps like Foursquare, which is also able to send push notifications when you check in somewhere. However, that assumes your friends are tech savvy enough to look up the location on their mobile phone and find their way there with whatever mapping tools they have.
In the future, I'd love to see Assemble add log-in hooks for Twitter and Facebook so as to not require signing up for yet another service. It would also be great to be able to send an e-mail or an SMS with your note to friends who aren't registered with the service, because as simple as it is to sign up, it's asking a whole lot for people to: have an iPhone (or iPod Touch), install this, register, add you as a friend, and have their push notifications toggle turned on.
Assemble is free, and weighs in at just under a megabyte. It works on both the iPhone and iPod Touch.