go to google and type "site:yourdomain.com"
no results?

I did that and I got plenty of results. So ismysiteindexed.com is crap then?

I wouldn't trust the results from that site if I where you. I just tried a site that I know has about 120 indexed pages, and it showed as not being indexed (the site is 5 years old).
Try SEOQuake or similar and you should get a reasonably accurate result.

You can use sitemap X to help you speed the index by Google. It's totally free.

Nowadays sites get indexed minutes within launch. I recently built a new site...by mistake I published a post that belonged on another blog of mine; post was up for about 3 minutes, I realized my mistake, and I deleted the post from the new site. I was going through the stats a week later, and I saw some 404 errors. I dug deeper, and I saw that google had indexed the post and people were clicking on it on google, and that led to the 404 error. Point is, your site was probably indexed long ago.

Try to submit it on Directory and search it on google the "site:yourdomain.com"

Your site is probably indexed but may not be ranked for the keyword term you wish it to. Work on creating high PR backlinks and submitting site to directories etc. Social bookmarking is also a great way to increase your rank in Google.

use site: operator to find the index page or use web rank toolbar addons in Mozilla browser.