Indention in HTML Sitemaps
It can be helpful to have links indented in a tree style way that match underlying website structure. Makes it easier to understand and navigate the website.

• Directory A
  • Page A
  • Page B
• Directory B
  • Page C
  • Page D

Columns in HTML sitemaps
If you want to take full advantage of page width to lessen scrolling, it can be useful to create sitemaps that use 2 or 3 column layouts.

Have sitemap span multiple pages with large websites
If your website is very large and you start to have above 100-200 links on a sitemap page, you should consider splitting your sitemap across multiple pages. Even if your users can navigate the HTML sitemap, search engines such as Google and Yahoo may start ignore links if you have thousands on a single page.

Page and section titles in website sitemaps
If possible, make sure each linked item in your HTML sitemaps have descriptive anchor text. This helps people and search engines to understand your website.

Create your website sitemap now
If you are looking for a program to do all of above, try this sitemap generator.