An idea that's been floating in my head for some time. I don't really consider myself a linux developer, butI know what I like, and I have some idea just what tends to attract users. So, without further ado:
Regina Caeli Linux J+M+J
Mission Statement: to develop a Linux distribution that helps Catholics live their faith in obedience to the Magisterium, and appeals to as many people as possible.
Papa Ben has said he wants the Gospel proclaimed on the Internet; surely this is part of it.
In omnibus caritas. Madeline L'Engle once said "We do not draw people to Christ by loudly discrediting what they believe, by telling them how wrong they are and how right we are, but by showing them a light that is so lovely that they want with all their hearts to know the source of it." This is how we make RC Linux appealing.
Ubuntu based; Ubuntu is easily one of the most appealing linux distros out there. Its ease of use especially contributes to this. Codenames could be taken from apparitions of Our Lady, e.g. Guadeloupe, Akita, Knock, the Immaculate Conception, La Sallette, Lourdes, the Angels, and so on.
We want it beautified; one of the most common complaints about Ubuntu is that it's ugly. This is important. One way that Catholics distinguish themselves from many Protestants (esp in these United States) is by getting beauty right. The Sabily team has made Ubuntu very beautiful (see review at http://www.extremetech.com/article2/0,2845,2347168,00.asp ). Surely we can do as well. Eye candy has a lot of appeal.
One idea I have for this is to set up an autotheming script, to theme the desktop in accordance with the colors of the Liturgical calendar: green, gold, purple, red, and rose. Themes should include color coordinated window decorations, highlights and selections, Clearlooks widgets, icons, and wallpaper.
DansGuardian fronted by Webstrict, or else pull MintNanny.
Software for the liturgical calendar (requires localization), Rosary, Liturgy of the Hours, Daily readings (requires localization), Saint of the day (requires localization), GnomeSword with Douay-Rheims Challonier and King James Version with apocrypha. Other devotional applets in the repos could include Ignatian, Sacred Heart, Immaculate Heart, the Infant of Prague, Sacred Blood, etc.
Customized IceWeasel -- not just customized homepage, but a whackload of links built in: apologetics, catechesis, spirituality, faith and morals, canon law, history, saints, etc.
Ad Majorem Dei Gloriam!
Random Thoughts: I sometimes think that part of the failure of Ubuntu Christian Edition was its attempt to appeal to (and so, in some ways reconcile) believers with utterly incompatible beliefs. Narrowing the focus to the One, Holy, Catholic and Apostolic church ought to help make this a better distro than Ubuntu CE.