Various categories worth looking into.

Tomorrow's Church.

http://catholicyouth.freeservers.com- Catholic Youth Networking.  A fantastic website for Catholic youth!
http://www.deadtheo.com- Dead Theologian's Society.  Sounds cool, doesn't it?
http://francescoproductions.com- Francesco Productions.  Fr. Stan Fortuna's website.
http://www.hnyouth.vze.com- Holy Name Youth Group.  A youth group in Topeka, Kansas.
http://www.lifeteen.com- Life Teen.  A Catholic youth revival.
http://www.onerock.com- OneRock.com.  I love it; my sn on this site is "floscarmeli."

Various Catholic traditions.

NEW!!http://www.monksofadoration.org/chapel.html- Adoration online.  Take a moment out of your surfing to drop in on Our Lord!
NEW!!http://www.isc-durant.com/lbaa/montfort.htm- Total Consecration.  The DeMontfort way, 33-day preparation and all.
http://www.carmelitehermitage.com/FreeScapular.html- Brown Scapular.  Why wear it?
http://www.rosary.org- Rosary.  Pray it.
http://www.familyrosary.org- Family Rosary.  The family that prays together, stays together.
http://www.prayrosary.com- Rosary/Scapular.  The two are inseparable.
http://www.immaculateheartofmary.net- Worldwide Rosary Crusade.  The Immaculate Heart will triumph!
NEW!!http://www.byzantines.net/- Byzantines Online.  Information on the Byzantine rite.
NEW!!http://www.catholic-hierarchy.org/- Catholic Hierarchy.  Information on the worlds bishops & dioceses.
http://www.for-torches.4t.com- Torch Enthusiasts.  Part 1 of 3.
http://www.triad-dev.com/church/- St. Joseph's Church in Topeka, Kansas.  The most beautiful church in the city (Holy Name is in second place in the beauty contest!).  Part 2 of 3.
http://www.triad-dev.com/torch/- Torch Emporium.  Part 3 of 3.
http://www.catholic-forum.com/saints/indexsnt.htm- Patron Saints Index.  Find that special someone who is praying for you... in Heaven.
http://www.marian.org/- Divine Mercy.  Info on the Divine Mercy devotion.
http://www.heartsare.com/- The Immaculate Conception: Gateway to World Peace.  In honor of our Blessed Mother.
http://www.pwhs-mfi.org/- Prayer Warriors of the Holy Souls.  Devoted to releasing souls from Purgatory.
http://www.thekolbegroup.org/- The Kolbe Group.  An email group.
http://halo-works.com/- Halo Works.  I know this is free advertising, but they have some neat things.
http://totallycatholic.com/- JMJ Products.  More free advertising, more cool stuff.

  -The Mass
http://www.lphrc.org/Mass/masstext.html- Interlinear Latin Mass.  Line-by-line translation of the Tridentine Mass.
http://www.latin-mass.org- Latin Mass in Kansas City, KS.  The St. Philippine Duchesne Community.
http://latinliturgy.com- Latin Liturgy Association.  Promoting the use of Latin in both the Tridentine and Novus Ordo Masses.
http://www.adaltaredei.org/- Ad Altare Dei.  Info on the Tridentine Mass.
http://www.latin-mass-society.org/- Latin Mass Society of England and Wales.  Una Voce in Europe!
http://www.omm.org/links/links.html- Opus Mariae Mediatricis.  Promoting the Tridentine Mass.
http://www.catholicliturgy.com/- Catholic Liturgy.  Info on the proper way to celebrate both Tridentine and Novus Ordo Masses, among other things.

My favorite multi-purpose Catholic websites.

***http://www.catholicity.com- CatholiCity.  My personal favorite.  Join email discussion groups, search their extensive links, read commentaries... wonderful!***
http://www.catholicgoldmine.com- Catholic Goldmine.  This is the best Catholic megasite.
http://www.cukierski.net/- Cukierski Family Apostolate.  This site has a little bit of everything- I highly recommend it.
http://www.vatican.va- Vatican: the Holy See.  All roads lead to Rome, as they say.