Persistence is a corner stone of all computer applications. The approach to persistence in an application **should** carry lot more weight than the frameworks that are normally used to display or manipulate that data. Persistence and Databases takes a new precedence with web where a variety of databases can all of a sudden open up new alleys to programability over the web.

This trend is evident in a number of multi-tenanted cloud based systems such as Salesforce or Microsoft Dynamics or Parse.

As a web developer these database are important to me because I salivate what can be done with each the strengths that each database bring to the table to push the programmable web by end users.

The goal is no longer where one database rules it all. Bring the diversity and exploit each for their strengths through the cloud.

Here is the link

The link above lists all databases ranked by their use

There are about 156 of those


oracle
sql server
mysql
postgresql
db2
mongodb
access
sybase
sqlite
teradata

Redis
memcached
riak
encache
dynamo db
simpledb
berkelydb
oracle nosql

cassandra
hbase
accumulo
hypertable

Mongodb
couchdb
couchbase
Ravendb

Neo4J
Orient DB

Jena
Sesame
Redland
AllegroGraph

Marklogic
Sedna
Tamino