Web 2.0 enables and facilitates the active participation
of each user. Web 2.0 applications and services allow pub-
lishing and storing of textual information, by individuals
(blogs) and collectively (wikis), of audio recordings (pod-
casts), of video material (vidcasts), of pictures, etc. Au-
thoring of this user generated content is greatly facilitated
by providing easy to use desktop-like interfaces. While some
time ago, Web applications were easily distinguishable from
their desktop counterparts due to their design and point-
click-wait interaction, today's Web 2.0 applications are of-
ten recognizable as being Web application only at second
glance. Due to techniques such as Ajax and Flash, responses
from the user interface now behave similar to desktop appli-
cations (as long as a fast Internet connection is available).
Additionally, Web 2.0 services typically put much eort in
usability and aim at simplifying the interactions as much as
possible by concentrating on the task or service the applica-
tion provides. Customers often have several similar services