One of the most common mistakes we come across in regards to Search Engine Optimization (SEO), is that most sites contain only one sitemap. Your sitemap is used for search engines to identify pages across your site, which greatly enhances crawl rates and indexing of your website. The more pages you have indexed, the more likely your content is to be found in search engines. Thus why not use multiple site maps to separate out content on your site?
The Why
Now lots of people say "Oh well my site isn't large enough for multiple sitemaps." But doesn't your site have a blog? Might your blog need a separate sitemap? Or sitemap for a section of articles or resources?
One of the biggest reasons for separating these out, is so that you now exactly how many pages in each section of your site are indexed. It would of course be a lot easier if big'ol mean Google would just tell you within Webmaster Tools. But hey they're not. So it makes sense to break your site down into multiple sitemaps so you can easily see what on your website is indexing and what is not.
You can see above that by separating out the sitemaps that we know 98% of our blogs have been indexed by Google. If these weren't separated how we would know? How do you know if your blog is indexed?
The How
Creating Sitemaps is pretty easy, I recommend the XML sitemap generator over at www.xml-sitemaps.com. For simple sites I recommend at least separating out your blog separately from your main site. If you have a separate section for articles, I would do one for it as well.
For larger more complex sites, for instance an e-commerce site with hundreds of product pages, you might have a sitemap for each primary category and possibly subcategories. That's for you to decide.
The Results
With this practice, not only is it easier to analyze your websites indexing, but your website will more than likely have more indexed pages and index new pages faster.
The same holds true with Yahoo Site Explorer and Bing Toolbox. Each allows for submission of multiple sitemaps of your website. Note that Bing Toolbox is at least nice enough to actually show you the indexed pages in the Index > Index Explorer section, but don't expect them to automatically start indexing a separate Blog Sitemap. I recommend that you monitor this section and physically look to see what is being indexed. You can manually submit your URLs since they allow for 50 direct URL submissions a month or 10 per day.












Comments
Google API to automatically create separate accounts, etc, if you want to get that fancy and have a huge website (or many).