martinibuster - 5:11 am on Mar 30, 2010 (gmt 0) [edited by: bill at 2:52 am (utc) on Apr 2, 2010]
I would try to find a way that wouldn't allow anyone to post a URL, even if it isn't an active link, until the destination was reviewed and determined to be relevant/helpful -- through means of automation or human eyes ($$$)...and/or...
The intent of your idea is good and has merit but the application would prove impractical. Discussion and membership satisfaction would dampen if members could not link out to a news source, to an authoritative source of information, to photos, and to citations from other websites.
There are workarounds that minimize the spam problem such as stopwords, active moderation, a system for banning problem IPs, a bot-stopping challenge and removal of profile links. With all that in place the spam problem gets whittled down pretty fast.
[edited by: martinibuster at 5:22 am (utc) on Mar 30, 2010]
[edit reason] tidy up [/edit]
[edited by: bill at 2:52 am (utc) on Apr 2, 2010]