I made a Greasemonkey script for enhancing Hacker News user profiles:
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http://alteredqualia.com/visualization/hn/hnuserprofile.user.js
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It does two things:
1. Change URLs into clickable links.
2. Show user's topcolor (if indicated by "my topcolor is xxyyzz" or "topcolor: xxyyzz")
It's far from perfect, but it should work for majority of cases. I tested it on leaderboard profiles, where it fails only in one case.
Note: Linkification is opt-in and client side, so it shouldn't interfere with the original reason for not allowing clickable links in profiles (to disincentivize spammers).
http://news.ycombinator.com/user?id=jrockway
http://news.ycombinator.com/user?id=comatose_kid
http://news.ycombinator.com/user?id=tsally