I did the baby center app, I could take it or leave it. Not that great. I downloaded Contraction Master for when I go into labor. I'd be interested in if anyone has recommendations for a feeding app? With DD we didn't have smart phones so we used pen and paper then transferred to a spreadsheet. We only did it for the first 2-3 weeks if I remember... until we were comfortable with how BFing was going and we knew she was gaining well etc.
I downloaded contraction master for my iPhone but I don't use it because I find it's really glitchy and doesn't save my info half the time. According to their website, they have a companion app that lets you track feedings similar to how you'd track contractions which seems neat. I have another contraction app on my phone called Full Term that works well. I've used it to track my PTL signs and I like that I can add notes/the intensity of the contraction and email it to myself.
For BFing with DD, I had a notepad app on my phone that I would just put the info into. For instance, I'd write L 10:00-10:15, R 10:20-10:25.