Every small piece of information that you want to memorize, create a new card.
Let me give some examples from my current technical deck:
Q: This is an open source data collection system for monitoring large distributed systems. It's a distributed data collection and analysis system in Hadoop. It runs collectors that store data in HDFS and it uses MapReduce to produce reports.
A: Chukwa
Q: This is an Apache templating language and processing engine that can be used to generate Java code, HTML, JSP's, Hibernate modules and most anything else that can be generalized.
A: Velocity
Q: In Ruby, what command lets you determine whether you're running as a main program?
A: if __FILE__ == $0
Q: This C++ function rearranges the elements in the range [first, last) into the lexicographically next smaller permutation of elements.
A: prev_permutation