• Distributed Computing:
  Fault-tolerant systems, State Machine Replication
  Large-scale networks, p2p & DHT infrastructures
  
• Internet technologies:
  HTML, DHTML, Javascript, ASP, PHP, SQL, Flash etc.
  
• Programming and scripting:
  Java, C, C++, Bash script
  

Music:
Guitar
Classic: Degree of classic guitar (June 2006)
Electric: Mainly rock, with tensions to blues and jazz
Rythmic: Greek rock and soft rock
Harmonization
Degree of harmonization (June 2005)
Sports:
Volleyball, Tennis, Table-tennis, Sailing
Various:
Rubic's cube