HitBox - HitBox is
the most popular Internet-based Web audience analysis service on
the market with more than 125,000 active users. It provides numerous
real-time statistics designed to tell Webmasters the "who,
what, when, and where" of every visit. HitBox is free with
the inclusion of a HitBox banner on each monitored page.
Site Meter - Site Meter is a free, fast,
and easy way to add a web counter to your web page. Not only does it display
the number of visitors to your web site, it also keeps statistics on the number
of visits each hour and each day.
W3C Markup Validation Service - A free
service that checks Web documents in formats like HTML and XHTML for conformance
to W3C Recommendations and other standards.