General Sites on the European Monetary System

The European Parliament’s fact sheet, a concise summary:
www.europarl.eu.int/factsheets/5_2_0_en

Sites and papers evaluating the European Monetary System

The title says it all: 'The European Monetary System (1979-1988): achievements, flaws and applicability to other regions of the world', a paper by a leading international macroeconomist, Peter Bofinger.
www.unescap.org/drpad/projects/fin_dev/bofinger.pdf

Sites on exchange rate crisis (like those that plagued European Monetary System in the 1990s)

Crises and regimes are debated on Professor Roubini’s website. See especially the page of links on 'Other Episodes of Fixed Exchange Rate Collapse in the 1990s: The ERM Crisis in 1992-1993 and the Tequila Effect of the Mexican Peso Crisis in 1994-95':
www.stern.nyu.edu/globalmacro
(Look under 'Exchange Rates', then 'Fixed Rate Collapse'.)

Sites and documents on the ERM-II

See the paper concerning Czech participation in the ERM-II and Euroland membership, 'ERM II and the Exchange-rate Convergence Criterion: Information material for the Czech Government'. This is from the Czech National Bank (i.e. Central Bank).
www.cnb.cz/en/pdf/ERM_II_vlada_15_07_03_en.pdf

Most of the Central and Eastern European countries that are joining the EU in 2004 want to join Euroland as soon as possible and their central banks have begun preparing the ground; if you are interested in a particular nation, see the website of its central bank. Here is a page with links to them:
www.bis.org/cbanks.htm

A general description by the European Commission:
europa.eu.int/scadplus/leg/en/lvb/l25047.htm