Device agnostic mobile web development
If your project involves development for mobile devices you’ve got a choice to make: take a web-based approach or pick a platform and develop a native app. The former will likely be the quicker approach (unless you’re a gun Android/iOS developer already) and give you a chance of getting something workable hacked together in time.
On the hybrid web-native side of the equation PhoneGap, Cordova, and Ionic are all excellent tools for writing apps in HTML, CSS, and JavaScript that can be packaged up to run as native apps on any device.
If you want to stick with the pure web app approach Sencha Touch and jQuery Mobile are both easy to pick up and use.
Backend frameworks for native apps
Going down the path of native application development can give you a really slick looking project, but it does give you a lot more to consider than a simple web app might. Helios and Parse are two backend frameworks that’ll take care of analytics, notifications, social sign on, and more.