To ping or not to ping.?

I use GSiteCrawler to build my sitemap.
Each time I add a new page, I just update the sitemap which is super easy to do with the program.
Each time I do that, it gives me the option of pinging the updated sitemap to google.
I always choose yes because i never really update the sitemap more than once a day, often less.
But, is there a limit to how much one should ping?
If I update my sitemap twice a day, should I ping each day or does it in some way annoy google?

Ping your site as soon as you made an update on it. If you wish to have update your site not only once, then ping it after your last update.

Ping it when you've made some updates on your site...it's like you're making a signal to the spiders that there's "something new" in your site...

Can it increase your backlink?

ping cannot increase backlink but traffic. you need to ping your blog at least everyday so as to update the new blog post and crawl the new post.

i guess it is needed to notify services like technorati for new updates and posts so that SE's crawled it

ping can crawled you faster.