When using Creole for markup, creating an external link appears to be impossible. Neither \[[Outside URL|http://example.com]] nor <<http://example.com>> nor \[Outside URL]\(http://example.com) work. The first gets rendered as a broken WikiLink, the second get eaten and the last is not parsed in anyway so you end up with that exact text in your page.
I'd have made this as a Creole page as a practical demonstration, but that doesn't seem possible here. Here's a page with an example: <https://www.icanttype.org//demo/CreoleExternalLinks>
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+Looking at my example it seems that this is now [[done]] at least in 3.20100815.7 (Debian)
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+[[!comment format=mdwn
+ username="http://profjim.myopenid.com/"
+ nickname="profjim"
+ subject="comment 2"
+ date="2011-06-12T20:20:13Z"
+ content="""
+Done, thanks. --Profjim
+"""]]
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+[[!template id=plugin name=pandoc author="profjim"]]
+
+This plugin enables Markdown processing using [Pandoc](http://johnmacfarlane.net/pandoc/). You can configure it for Pandoc to take over processing of all .mkdn files, or only files with a different extension. Given the features Pandoc has added over the past 6-12 months, this makes for a very powerful combination, e.g. with code block syntax highlighting and lots of options for how to process and display inline TeX.
+
+This is an expanded and updated version of [[Jason Blevin|users/jasonblevins]]'s pandoc plugin. Get it and see further details at <https://github.com/profjim/pandoc-iki>.
+