Rel=Canonical

[SoulSurfer8]

Any downsides to adding the rel=canonical tag to the canonical page itself? It will make it easier for us to implement based on the way our site's templates work.

For example, we would add to the page http://www.mysite.com/original-page.aspx

The canonical tag would also appear on other dupe pages like:

http://www.mysite.com/original-page.aspx?ref=93929299

http://www.mysite.com/original-page.aspx?ref=view29199292

etc

[john4math]

Google doesn't care, but Bing may not like this.  Read http://nickroshon.com/seo/google-bing-disagree-on-relcanonical-implementation for more info.

[NakulGoyal]

IMO that's completely fine. You are passing a directive to Google telling them that whatever versions of that one URL they may come across, the correct URL for them to index, crawl and display in their SERPS is the "original-url". So you are good.

[My-Favourite-Holiday-Cottages]

Google is definatly OK with this, Bing aparently might have issues, but the only way around that would be implimenting it for all the dupe pages but not the original (which is less trivial to detect, or impossable, and why google allows it)

Due to the nature of the objection (Bing claims your telling it that the page is a duplicate of itself, see the article John linked), I would actualy expect Bing to change that in the future to something more sensable if true.

Overall, I would impliment it on every page just to prevent all those links to it with random tracking paramiters e.t.c. that people could throw on.

[Dr-Pete]

I haven't seen any evidence that it's a problem, but John's point is correct - Bing does officially say not to do it. Actually, Google originally said this, too, but then eased off (if I recall correctly). It's gotten so common that I don't think either engine can really penalize it, honestly. I do it all the time.