Low Description
The JDBC Driver suite needs support for BigDecimal to complete it's data type support for ResultSet and PreparedStatement. This datatype could also be used to represent numeric (non-integer) counter values. This is a very simple addition to the collection of data types supported by Cassandra. It is quite versatile like BigInteger. It can represent decimal numbers of virtually any precision and scale. It is represented in Java as an arbitrary precision integer unscaled value ( think IntegerType )and a 32-bit integer scale factor, which could be represented as a IntegerType as well. This could share much of the logic from the BigInteger (IntegerType) implementation.
CQL would need to add a datatype (decimal?). Decimal literal support is already provided in CQL.
This is low hanging fruit.