Ping them. Create an RSS of them and submit that to feed directories. Backlink to them with scrapebox or xrumer or something.
Yeah it is a great idea to ping your back links and to submit it to different social networking sites
Ping & Social Bookmarking (ie Digg). Also, ensure you have a valid sitemap to get the entire site crawled ASAP.
Submit your backlinks to social bookmarking directories and Ping them both techniques are so useful for indexing backlinks.
search engines are pretty smart to index links .... i don't think one need alternative methods for this purpose .
Just perform SEO on high Page rank sites and stop worry about indexing your submission because high page rank sites stuff get automatic indexing with indexing site.
Submit ur site to good page rank sites and checke wether the previous comments links are dofollow or not if its do follow try to be in that discussion and follow the best practices. And never ping ur site after a limit there is a chance that ur site may get de indexed also.
I wouldn't worry too much about it, if it's a link worth having, google and other search engines will find it. If you need to notify google that the link is there, it's probably not worth much anyway.
Pinging by itself isn't going to cut it these days. You really need to build backlinks to these links in order to get them indexed. You can automate this process using http://BacklinksIndexer.com