Geocities has blocked off-site images since the beginning of time, AFAIK. I have no reason to believe they weren't blocking everything except .HTML links since the start either.
It's just the way it is. Web-accessable disk space at the cost of no direct links, silly ads, and $0 for the poster. Take it or leave it.
I fail to see the problem with the way they operate. It's not like the ads are self-replicating popup/unders. The ones I've seen (on my own Geocities site) aren't flashy, seisure-inducing annoyances, and even have a minimize/close button that
actually closes the thing!
PS: pasting the url into your browser is the same as clicking it. You need to go to your geocities site, and
then paste the link.
Or, just make a simple 1 kb HTML page which displays the images, and link to the HTML page.
Or, upload the images to shrapnel, seing as they are on topic here.
EG:
http://www.geocities.com/hohoho611ca/ships.html