Image of Selamat Datang Monument, Jakarta, Indonesia © Mike Aquino, licensed to About.com.
In Jakarta, Indonesia, I used my trusty Nokia E72 smartphone (compare prices) with Google Maps installed. Thanks to Google Maps, I was in the unique situation of being a total Jakarta n00b, while giving directions to my taxi driver like a pro. The taxi driver didn't know where my destination was; luckily I'd saved the location as a layer in Google Maps, allowing me to show the driver exactly where I wanted him to go, and checking up on our location to make sure we were getting closer (not further) to the place I wanted to visit.
But first you gotta have a smartphone, and second, you gotta have a local prepaid SIM loaded up with credits. I had a Telkomsel SIMpati prepaid SIM (Google Translate of site) costing IDR 20,000 (about $2.50), each of which comes with IDR 5,000 (about $0.60) in credits. I got a SIM card as well as an additional IDR 50,000 (about $6) in additional call credits.
Now here's how I wasted good money: apparently with Telkomsel SIMpati, buying Internet credits is another step entirely. Because I didn't buy Internet credits (or in Indonesian prepaid phone lingo, "flash"), I ran through the IDR 55,000 in a few minutes flat, just by checking my Facebook mobile page. Big mistake.
What I should have done, immediately after I got the SIM up and running on my phone, was to buy "flash", or blocks of usable megabytes, which are usually deducted from the SIM's prepaid balance. To find out what I should have done, read this article on using Telkomsel's SIMpati GSM Prepaid SIM card in Indonesia.