Liturgy Training Publications - they also publish the Lectionary, including a less-expensive "Study Edition," and provide many other excellent resources for liturgy, including:
Martin Connell's Guide to the Revised Lectionary (Basics of Ministry Series, 1998).
Liguori Publications - formerly published a CD-ROM of "The Lectionary for Mass: Volumes 1-4" with the 1998 Sunday and 2002 Weekday readings (out of print?).
Lectionary Links for Other Countries, Churches, and Denominations:
Lectionary Resources for the Episcopal Church- readings available for download in RTF format (Roman Catholic readings also, but using the NRSV translation); includes tables of readings for Liturgy and Daily Prayer in upcoming weeks, and monthly overview calendars; by Charles Wohlers
Liturgy of the Hours - daily morning and evening prayer, in easy-to-use format; by "Liturgy of the Hours Apostolate"
Living Space - commentaries on the daily readings; from the Irish Jesuits
The Sunday Mass - website related to weekly TV broadcast; from Passionist Communications
Meeting Christ in the Liturgy - including "The Word on the Web" with "weekly reflections on the Scriptures of the sacred Liturgy and the Catechism of the Catholic Church"; in English and Spanish; choice of old Roman Rite liturgical calendar (1962) or post-Vatican II liturgical calendar
This Weekend - scriptural readings, reflections, questions, prayers, etc., from Fr. Patrick Umberger, Plover, WI
Universalis - focusing on the Liturgy of the Hours and the Psalms, but also contains daily Mass readings
Word of God - meditations "to help you prepare for the coming Sunday's radings"; by Fr. John Mole, O.M.I., Canada
Ecumenical Resources for Biblical & Lectionary-Based Preaching:
The Text This Week - "Revised Common Lectionary, Scripture Study and Worship Links and Resources for Students, Teachers and Preachers"; an extremely good site with many scriptural resources for each week's readings and each biblical book; by Jenee Woodard
Desperate Preacher's Site - click on their "lections" link, then scroll to any day from Jan. 1 to Dec. 31 of the current or past years
iFindSermons - sermon service with downloadable full-text sermons (topical, holiday, wedding, funeral, etc.) on individual or subscription basis; free newsletter, and hundreds of jokes, quotes, illustrations, sample sermons and Bible study resources.
Liturgical Year Calendar - nicely organized interactive liturgical calendar; from "CyberFaith", an e-zine for the Catholic Community, from William H. Sadlier, Inc.
Liturgy Planner Online - online version of liturgical planning for every Sunday and Holy Day, RCIA, Children's liturgy, hymn suggestions, articles from U.S. and Canadian Bishops Conferences [commercial site]