I figured out this little tip when I flew to Berlin last year to visit my cousin and walk around the city a bit. I took a bit of time for myself to walk around the city alone and unfortunately the hotel I was staying at didn't offer free WLAN - instead you had to offer your first-born son, two fingers, two toes and a piece of your soul to get Internet. No problem if you have an expense account, but a bit of a drag when you value life and limb. But I digress... I hate walking around a foreign city with only a large paper map to guide me around and no way to find any more information than a guide-book offers me. There's nothing that screams "TOURIST!" more than standing on a street corner with a large map held out in front of you, trying to figure out if you need to make a right or a left turn. Large maps are also so difficult to use in a snap: you have to unfold them, find your location on the map and then navigate. Now, I have an uncanny sense of direction and can get around just fine in a foreign city, but if I can make my life a bit easier, then I most certainly will do what I can.
My solution to this little conundrum of how to get Internet and avoid looking like a tourist was found in the form of a prepaid SIM card from Vodafone. I paid a small sum (around €10 if the offer hasn't changed since then - I honestly don't remember what I paid) and got 200MB, unlimited SMS and 100 free minutes, along with a €15 credit to the card. All I had to do was pop the card in my phone and then I was online. I had Internet for the few days I was there (200MB is enough for my mobile needs) and was able to use Google Maps without any issues.
Right now, I'm currently waiting to board my flight from Vienna to Berlin and before I left, I decided to look up what telecom network is the best for data in Berlin. Thankfully (or perhaps not?) the selection doesn't seem to be quite so large, so I was able to figure this out in a pinch. It also helps when there are regular tests (German article). The result of the test: go with Vodafone or T-Mobile if you want reliability and speed (O2 was slightly better than Vodafone in terms of telephone reliability).
I'm going to go with the Vodafone offer since it offers the most "freebies" over the T-Mobile card. The network differences aren't that huge and for my needs almost irrelevant. The unlimited SMSs within Germany and the flat rate for calls is also nice. Highly doubtful I'll ever actually need all that in my few days but it's nice to have.
Time to board now, though - catch ya later!
PS - I went ahead and went with the Telekom (T-Mobile) offer. The woman at the Vodafone shop didn't seem to understand what I wanted and I didn't want to sort it out. I was in a hurry and went next door to Telekom and got it worked out in less than 5 minutes.