You can use GSiteCrawler to create a sitemap. They are helpful with making sure your site is spidered.
If you have a really small site, it won't make a difference. Otherwise, you can just create a text file with the urls to each of your pages and place a reference to it in your robots.txt file and Google will eat it up. Best to use a standard xml format though. There's any number of free services that provide sitemap generation. Try to find one that is Google and Yahoo friendly and you'll be in good shape. By doing so, you can be reasonably assured that any search engine will benefit.
if u create sitemap and submit in google webmaster tool so google cache every page regularly and which error come in which page every information get google webmaster tool also u submit your sitemap in off pages ways so its very effective
Creating the xml sitemap for your site using xmlsitemaps.com and submitting it to google webmaster tools makes your site webpages to index very fast.
hey just Google it . Most of people use xml-sitemaps.com which is really cool i feel. This will help G to crawl easy .
if you're using a wordpress powered blgo - you can look for worpdress plugins which can generate you an automatic sitemap page (both xml and php/html)
There are many tools to create sitemap. If you are using WP then you can easily find sitemap generator free plugin. Submit the sitemap to Google webmaster tool and its good for getting your website indexing.