The fate of an accepted paper not being presented
This has actually happened to me a couple of times in the past. This really depends on the policy of the organizing professional group (ACM/IEEE) and even within sub-groups of that body (SIGWEB/SIGCHI within ACM)

Generally, I have found that if your paper is accepted in a conference and you or any of your co-authors register for that conference, then the paper will still be published in the conference proceedings and indexed in the relevant digital library. e.g. IEEE Xplore, ACM Digital Library etc.

If you or a co-author do not register for the conference, then your paper, in general, will not be indexed. 

If an accepted paper is not published in the conference proceedings (and by extension not indexed in the appropriate digital library), then it generally does not "count" as a valid publication. You are better off, in that case, by withdrawing your paper and submitting it at a more acceptable conference venue (or a journal where there is not travelling involved)  

PS: You can always link to such a paper on your personal website or put it on arxiv for comments. Google Scholar will obviously index it but such indexing has limited practical value.