Languages
- Java
- Scala
- HTML, XHTML, CSS
- SQL
- XML (XPath, XSLT)

Databases
- MySql
- HSQLDB
- H2
- Postgress

Big Table like database (NOSQL)
- Cassandra
- CouchDB

Graph databases
- Neo4J

ORM
- Hibernate, JPA

Webservers
- Tomcat
- Jetty
- Apache 2.0

Web Frameworks
- Wicket
- Lift
- Spring MVC
- GWT
- JSF
- Struts

IoC
- Spring
- Guice

XML
- XStream
- XMLBeans
- JiBX
- Xerces
- Saxon
- JAXB
- Jaxen

SOAP
- CXF (XFire)
- Axis2

ESB
- Mule
- ServiceMix
- Synapse
- Camel
- Progress Sonic

JMS
- ActiveMQ

Build and managment
- Maven
- Ant
- Hudson, TeamCity, Sonar

Search
- Lucene, Solr
- Hibernate Search
- Carrot2
- Compass

Caches
- Ehcache

Clustering
- Terracotta
- Sequoia

Testing
- JUnit
- Mocked
- HttpUnit
- SoapUI
- JMeter
- Mockito

IDEs
- Intellij Idea
- Eclipse
- NetBeans
- Stylus Studio

OS
- Windows, Unix (Ubuntu, Debian, FreeBSD)

Control Version Systems
- Subversion, Git, CVS

Methodologies
- Agile methods (scrum, TDD)