Hmm, interesting idea.
I've actually been thinking of registering "mywife's-family.org" in order to just let the "old timers" record their memories of generations past, and to give the rest of us a place to meet besides once a year at the lake in July. Some of us, being now on the verge of actual adulthood (whenever that starts<?>) are getting more interested in such things.
So, it'd be a forum, maybe a little CMS for "articles," etc.
OTOH, this doesn't exactly sound like what you're talking about....have they given parameters? Actually, you're probably talking to folks who just want "something" and aren't able to give you any params....
If you're actually wanting to store data, you'll need quite a schema. See if any of them can give your their paper charts. Certainly you'd want at least this:
column name | data type
------------+----------------------------------
id | integer
first_name | text
last_name | text
dob | date
dod | date
mother | integer (relation to other row, this table)
father | integer (relation to other row, this table)
--------------------------------------------------------
This is probably too simple---most people want to know ~nee and children, with children's birthdates, dates of marriage(s), etc. etc.
There is a PostScript document at [URL=ftp://ftp.gedcom.org/pub/genealogy/gedcom]ftp.gedcom.org/pub/genealogy/gedcom[/URL] that describes the database schema used for the Gedcom SW. Reading about the web, it seems lots of folks think that adopting this schema for a single-family tree might be overkill, but it might be worth a look. Another possibility might be just using their SW itself, but that may or may not be what you desire. They do have a converter (GED2HTML) that makes direct conversions from their SW to HTML. That's at gendex.com.
I might also be interested in any other opines on this subject, in case I do ever register "mywife'sfamily.org".....