jog.fm - Workout music at your running pace ($1.99) by Blendist LLC will drive your run and give you a speed boost. Let your music motivate your run without ever having to fuss with playlists. Let Jog.fm do the work for you instead.
First things first, let the app scan your music library. It only took me about 10 minutes, but it will be different for everyone (based on how big your library is).
I was in the experimental stages with this app. I fired up Nike+ GPS. Jog.fm was still working, running in the background, and playing the tunes. Cool! I set up my run criteria and pressed play in the Nike+ app. Jog.fm immediately stopped playing. After being disappointed for a moment, I opened Jog.fm back up and restarted it. This made it so that I could successfully run both apps simultaneously (just start Nike+ or Runkeeper first).
Also, make sure not to lock your screen with your phone's button; use the lock button in the app to do so.
Now, I am no marathoner. I have never ran more than six miles at once and I'm pretty slow, but I'm getting there. In fact, I had taken a brief running hiatus due to the excruciatingly hot weather. I was out of practice. That's why I was so excited when a friend informed me of this app: here was my motivation!
You just start it and go. Pretty easy, right? It really does drive your workout with the music it picks for you. I did find, however, that sometimes the music played seemed just a bit slower than my actual pace. Luckily, you can adjust the pace in the app with the up and down arrows. Essentially, these skip to another song with higher or lower beats per minute (BPM).
The best thing about this app is that it learns what music you like running to. Of course you'll skip a song once in a while, but if you skip it very often, Jog.fm will notice and completely take it out of the running (see what I did there?).
Jog.fm will only play music from your iTunes library, but that's what I like; it plays my music. For me, it seemed to play a lot of Nine Inch Nails and Sublime songs — many times — but hey, I am okay with that.
You can flag songs to either never play them again, or play them more often. You can set a constant pace, if you prefer, as well as warm up and cool down songs. Even set up a "Power Up Song" to play when you need that extra kick in the rear.
I was very impressed with Jog.fm. I am really glad it works with the Nike+ apps or else I wouldn't be using it as I use Nike+ to track my runs and my progress.
If you find yourself needing some motivation, or just a boost to get you going faster, I would suggest you give this app a try. It's currently on sale in the App Store for $1.99 and I think it's worth it.