Site wide credit links for webdesign site

is it good to have such site-wide credit links or they should be restricted to the home page only

bump

I personally would love if WordPress could offer this option, or maybe I just need to figure out some nice CSS or javascript for it!? lol

I think it's best one link unless you want to actively promote the service on your own sites. Maybe on client sites, it would be overkill, as I think if they looked, they would feel it was more professional that you only expected a single link. Not leech on to the rest of the pages on the site too.

You definitely don't want a bunch of sitewide links from different websites nowadays. One of the many updates a few years ago specifically addressed this, as many design agencies were exploiting these kind of links.

All my experience with site-wide links was negative. It can only be useful if natural (like linking to other language version, or to website creator site), but don't expect any super results from that.

Another option is an <img ...> link with alt text