Apache Flex

Apache Flex (formerly known as Adobe Flex) is a set of software tools and libraries for the development and deployment of Flash-based, cross-platform RIAs (Rich Internet Applications). The user interfaces are created using MXML (an XML-based markup language) and the tools from an SDK which is available from Adobe for free.

Advantages

More suitable than Flash to create UI applications
Supports stateful applications
Does not require deployment (it creates live applications)

Disadvantages

Lack of support for accessing local files
Lower performance when dealing with many data records

Components

LiveCycle Data Services
BlazeDS
ColdFusion Extensions

Development tools

Adobe Flash Builder
Adobe Flash Catalyst