Mobile web apps now can be incubated from many great javascript frameworks and supplementary libraries. It maybe a bit slow and quirky comparing to native apps but obviously cross-platform HTML5 mobile apps could help to have multiple versions of apps within no time. Perfect for small and medium sized apps. Plus those frameworks and libraries have a full featured list of functions, even if you don’t know much about HTML/CSS(Maybe not in reality..), you would still be able to build an mobile app/website.
Followings are some fully-featured javascript mobile frameworks and small js libraries good for mobile app development. They’ve been used by many users and many tutorials/helps are available on the web, so you can get a quick start with them.
8 Mobile Javascript Frameworks
1. Sencha Touch 2

Sencha Touch 2 is a high-performance HTML5 mobile application framework. It’s built for hyper fast speed and responsiveness and is the only framework that enables developers to build impressive apps for iOS, Android, BlackBerry, etc on both Mac OS and Windows system.
2. jQuery Mobile

jQuery Mobile is dedicated for HTML5 mobile device platforms, built on the jQuery and jQuery UI foundation. It has lightweight code library and flexible theme customisation.
3. PhoneGap

PhoneGap is another great HTML5 app platform to build hybrid mobile applications using Javascript, HTML5 and CSS3
4. dojo Mobile

dojo mobile is part of dojo javascript core framework. It can be used along with PhoneGap to distribute the developed web app to AppStore apps.
5. qx.Mobile

qx.Mobile is part of qooxdoo javascript framework. It’s suitable for iOS and Android web browsers. It provides specific UI classes and touch gestures.
6. DHTMLX Touch

DHTMLX Touch is also another free open source JavaScript library for building HTML5 mobile web apps. It’s a complete framework that allows you to create robust web applications that run on iOS, Android, and other mobile platforms.
7. Jo

Jo enables you to build apps using Javascript, CSS and don’t worry about DOMs. It’s made for mobile apps, not websites. PhoneGap compatible to package the app to an native-like app.
8. iUI

iUI is great for building websites/web apps with mobile UI elements/touch gestures on multiple mobile platforms.
4 Mobile Javascript Libraries (or Plugins)
1. Zepto.js

Zepto.js is used as minimum javascript library and easy-to-use API to help building awesome web apps. It supports many CSS3 transformations which enables creating awesome effects and animations.
2. JQTouch

JQTouch now is a part of Sencha and used as specific jQuery plugin for mobile web development. It is suitable for small screen devices which claimed in Sencha blog.
3. jqMobi and jqUI

jqMobi and jqUI are built for mobile app development. They’re also a minimum javascript library only 5k and 21k in size. jqMobi is a query selector library recognising existing framework like jQuery and ZeptoJS. It currently supports 60+ apis with jQuery compatible. While jqUI as the name says, it focuses on the UI element of mobile web apps.
4. XUI

XUI is a super tiny library if you just want some simple DOM manipulations, events handling and animations. It’s only 4.2k.
Please please add some in the comments if I miss any of those mobile javascript framework or you wanna suggest another great one.

Hello! Do you know if they make any plugins to assist
with SEO? I’m trying to get my blog to rank for some targeted keywords but I’m not seeing very good results.
If you know of any please share. Appreciate it!
Another good framework is Wink Toolkit: http://www.winktoolkit.org