I've been using FitDay online and PC for years but I now use my mobile Droid devices more and more. I was very surprised (and disappointed) that there is no Android app for smartphones and tablets seeing as the competition (fatsecret, LoseIt, Cronometer, etc.) have had these apps for some time now. FitDay used to be #1 but it's not keeping up with what users want and need.
Hopefully, the Droid apps will be released soon.
ETA: Curious that I've been a member of FitDay since 2006 yet it says my Join Date is 2012.