I’ve been using some add-ons for FireFox that enable me to investigate semantic mark-upon any given page if there is any on there. It’s good because it means I can begin to see which sites are all out on Semantic web and which ones aren’t yet. I’m definitely seeing a move towards more of that kind of data though. I thought I’d share with you some of the extensions that I either use now or have used in the past which I found to be useful.
- Semantic Radar: Displays a status bar icon to indicate presence of Semantic Web data in the web page. It recognises FOAF, SIOC, RDFa, DOAP.
- Operator: Lets you combine pieces of information on Web sites with applications in ways that are useful.
- SimilarWeb: Get related articles while reading one and read web comments of sites you are browsing.
- HeadUp: Helps you discover new content and boosts your social networking experience.
- Fuzz: It detects RDFa in any web page.
- Tails: This one detects Microformats in any web page.
- Clear Forest Gnosis: This one is for older versions of FireFox but it uses the OpenCalais infrastructure and locates key information hidden within the text.
These are a nice way to get acquainted with all the semantic code out there. Have fun 
Just what I was looking for. Downloading and installing them all one by one. Thanks guys!
Good list of apps that are semantic in one way or another. Some of these are pure semantic web apps that leverage standard markup e.g. RDF, FOAF, etc. while others (e.g. Headup, Gnosis) use semantic intelligence to infer useful insights from content.
I’d like to recommend MashLogic as one of the latter kind. You can install the extension from http://mashlogic.com.
Thank you for these new webmaster tools.
Best regards.
Good list of tools for Firefox.It is the best browser for IM use, IE does not have a chance.