I just got a Droid X (well it's my wife's phone but I borrow it for stuff like this) and started using Cardio Trainer. I think it's pretty good but see many mentions of other similar apps for running, walking, biking, etc. and wonder if I'm using the one that's best for me. Searching around some I see many reviews and recommendations, but haven't found a good compare and contrast, so if you can link one that'd be appreciated! Barring that, I'd like to start putting one together, so here's a very raw first cut: Cardio Trainer - Works well. Workout screen has data (speed, distance, etc.) widgets on top of the map that you can hide. Can give audio (speaks speed, distance, time, etc. at selected interval). Uploads tracks to to their website, you get a password for, can share them from there, 2 clicks to load in Google Earth. My Tracks - by Google. Looks like it displays map or plots vs. time of speed & elevation? Has audio, and of course upload to google (not real time?). Sports Tracker - lots of features and very customizable displays? Pro ver ~$10: upload live and recorded tracks to the website, view realtime performance and personal best info. Runner - by same people as Sports Tracker, is it a version pre-customized for running? Endomondo Sports Tracker - looks nice with lots of features and support, but does it have real-time: map? web update? Pro ver $4 adds "beat yourself - audio coach" RunKeeper - can toggle map to treadmill-style bar plot? Pro version adds Audio & some workout stuff, removes adds, is Free now. Buddy Runner - has map or info, voice. Auto Facebook/Twitter posting but no web site upload? Basic features, nothing fancy, but easy to use, and perhaps buggy?? SoftRace - looks good/mature. Shows map or data or a race display - race vs others or your previous tracks feature? Audio? Website upload? iMapMyRun - probably good since affiliated with mapmyrun.com (results sync to there)? SportyPal - looks like lots of features and nice details/map/graph tab? Audio?? Nice analysis on phone and web site, 1 touch upload. Pro ver free now, does what? SmartTraining - looks Korean? I'm only concerned with apps that GPS track here, though I know other categories of workout aiding apps can be great. The basic, useful features in my mind are displaying info (speed, distance, time, etc.) derived from the tracks, saying that info at some interval, track display on map during workout, and easy track upload, but am open to suggestions of other stuff. Oh, periodically uploading tracks during a workout so you can let people see your progress on the web would be cool also, if any do that. As far as actually using it, so far I've just held it in my hand and that's been fine - have done many runs holding a cheap fm radio or mp3 player this way before. Haven't done a long sweaty workout this way yet, and sweat kills electronics so I'm hesitant. I've seen discussion of armbands, so if anybody knows of one that works with a Droid X recommendations would be cool.