How to choose between Cassandra, Membase, Hadoop, MongoDB, RDBMS etc.?

Question

Is there a paper/blog-post on when to use Cassandra or Membase or Hadoop or plain old relational databases ? Is there a paper discussing the strengths/weaknesses of each, and on what scenarios either of these technologies should be chosen ?

I am thinking of writing a new webservice which will have about a million hits per day and data spanning about a few terabytes.

Solution

EDIT The NoSQL Ecosystem by Adam Marcus (from the book The Architecture of open source applications): http://www.aosabook.org/en/nosql.html

general thoughts and comparison http://www.thoughtworks.com/articles/nosql-comparison

technical comparison http://kkovacs.eu/cassandra-vs-mongodb-vs-couchdb-vs-redis

a Master's Thesis - Analysis and Classification of NoSQL Databases http://scholar.googleusercontent.com/scholar?q=cache:rQlbiz6bojAJ:scholar.google.com/+comparison+of+nosql&hl=en&as_sdt=0,5&as_vis=1