Links

Standards, specifications

List of all Java APIs (JSR's)
Entry to W3C web standards
RCF Editor (Official Internet Protocol Standards)

Java EE General

JEE7 Overview (Whitepaper from Oracle, some branding)
Different types of managed beans
CDI reference (Weld)
Bean Validation reference JavaEE 7 Samples (many and advanced)

Development

NetBeans
Maven
JavaDB, Derby
Git Tutorial

HTML

HTML5.1 Specification (draft)
HTML5 vs HTML4
XHTML vs HTML
HTML vs XHTML vs Polyglot HTML
HTML5 Compliant tutorial
HTML5 Compliant tag reference
HTML5 (CSS,JS) Presentation from Google
HTML5 Flowchart (what to use when...)

CSS

CSS reference
Bootstrap Components

JavaScript

ECMA (JavaScript) specification
JavaScript (core) reference
JavaScript in Detail, "this"
Gotchas

AngularJS
How to learn AngularJS
Jasmine (JavaScript testing)
JQuery API
HTML Landscape Overview (JS API's)
JavaScript Design Patterns
JavaScript API Demos (HTML5)

WebServices/REST

Metro (JAXB implementation)
JAXB annotations
Jersey (JAX-RS implementation) User Guide
SocialAuth
OAuth 2 In Depth
Article: Designing REST (HATEOAS)

Java Server Faces

JSF Home (Mojarra)
Nice overview article, JSF, CDI, ...
JSF tag reference
ICEFaces
ICEFaces ACE components
PrimeFaces
PrimeFaces components
Full version CRUD demo (also database), JSF PrimeFaces.

Java Persistence API

JPA Reference
JPA JPQL Reference
JPA CriteriaAPI reference
Easy Criteria

Client Server

Web Socket API Specification
Web Sockets Documentation MDN
Long-polling, Comet, etc. explained
ICEFaces push (PushRender API)
PrimeFaces push
Server Sent Events Specification
Atmosphere (Comet, Web sockets, Server sent events,...)