A suite of utilities for converting to and working with CSV, the king of tabular file formats
CSV Schema Language and CSV Validator
The National Archives (UK)
XSLT for converting CSV to XML: https://github.com/digital-preservation/csv-tools/
Data Pipes is a service to provide streaming, "pipe-like" data transformations on the web – things like deleting rows or columns, find and replace, head, grep etc.
Python's CSV module
It is part of the official Python distribution since version 2.3. Provides a simple shell around CSV files to read or write line-by-line, possibly use the header row's elements as keys. It is customizable to handle different separation characters (comman, tab, etc.). It uses Python's iteration model around the standard file object, meaning that it is usable with possibly large files.
Tablinker is an experimental software for converting manually annotated Microsoft Excel workbooks to the RDF Data Cube vocabulary.
PLSheet is a SWI-Prolog library for analyzing ODF spreadsheets.
Harmonize is a tool (prototype) for normalizing and aligning RDF Data Cube datasets, and getting CSVs out of it.