Google maps (street view)
It goes without saying that one of your best friends visiting any new city would be google maps. Apart from pinpointing your location and then being able to see map/satellite version to see just how far/close you are to major points, you can use Navigation to find directions to any street/monument/metro station, etc. The routes can re-calculate if there are streets closed/roadworks/you don't fancy the frst route suggested and you can even zoom in to street view with the pegman and actually follow the route as if you're following your camera.
|Street View Navigating to Palau Güell|
If there are a few of you in your group, you can also each turn on latitude, which will follow you around and if you decide to split up, you can "spy" on your friends to find out where they are - so girls go shopping and get lost from the boys, it's easy to find them again instead of wasting a call. Maps also lets you "check in" to places, similar to Foursquare and Facebook and similar sites, and then there are many apps to find useful places near to your location - the default one in Android is just as good as some of the others I've used, and will show you cashpoints/ATMs, Restaurants, pubs, petrol stations, etc.
|Fancy some food at the Boqueria, but don't have a guide book ?|
It also goes without saying that services like Viber, whatsapp and the like are also great for keeping in touch (but roaming applies, so it depends if your mobile plan works out cheaper/more expensive as many have bundle packets of sms thrown in). There are a couple of decent Wi-Fi Finder apps out there, too, to scan your surroundings and find free wifi hotspots to connect to and send messages to each other in these situations.
|Google Goggles Capturing Casa Batllò|
I really love this app. Apart from the possibility of taking a photo of (for example) a menu and having goggles directly translate the text for you, one of the best uses is pointing your camera at a random building and then Goggles will tell you what it is. It's surprisingly accurate and the photo here is even me in the car taken through the windscreen (as a passenger, don't fret) and the app recognised Casa Batllò in about 2 seconds. So instead of just wondering what that cool building is, flick out your googles. It is really really clever. Goggles also works perfectly as a QR reader, so those posters you'll see in and around the city for the upcoming nights in the cool Barcelona clubs can be a "Wonder if that's any good/wonder where that is?" thing of the past. I used it recently to find out more about the Cat Garden that I've passed by a million times and always wondered just who the cats belonged to and how they were taken care of, etc. For those of you not quite sure what those QR codes are, they're those black and white squares with lots of dots that work a little like a barcode.
|Conversation mode in Translate|
Twitter is an awesome social tool to have at your disposal. Before you go, make sure to do a bit of research and start to follow people who might be able to help. The social community on Twitter is mainly there to help and as long as you don't bombard people with usesless tweets you could easily find online, then most people are really willing to help. Hashtag searching can help, too, to see what's happening in #barcelona at any time, and some great people to follow are obviously Barcelona Yellow, Barcelona Guided Tours and Barcelona Unlike for up to date stuff and a keen eye on the city.
Obvously I've found a few other apps in the market, such as metro maps, etc. mostly free, as well as loads to do with FCBarcelona of course, but didn't include here as not everyone would use them on a daily basis. I'd love to hear any comments on apps or things on your mobile that you've used to help enjoy your stay or you think I should have included. Leave me a comment below!
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Disclaimer. I purposely haven't linked to the apps themselves, as this is not a promotional post or anything, just a helpful idea. You can find them easily in the android market.