What it does: Silk was designed to be a platform that combines blogging and structured data. In addition, an update to the service announced yesterday now lets users embed visualizations created on Silk on other, external websites.
As you might expect, you can upload existing data (in CSV format); but you can also create and add your own "collections" on the Silk website. A Silk collections is sort of like a database or spreadsheet table, with "tags" as columns and "pages" as records or rows. Add a tag to one page in a Silk collection and that tag automatically appears as an option in all the other pages (unfortunately, though, if you delete the tag field in one page, it still seems to appear elsewhere in the collection unless you manually remove them one by one.)
This 2-minute video from Silk shows how to create a simple collection:
Silk is more free-form than a database, since you can add paragraphs of text to some individual pages but not others.
What's cool: Silk mixes unstructured blogging with structured data, allowing you to visualize and query the structured portion of your information. "Explore" lets you generate a sortable table; bar, line or pie chart; or map (oddly, Silk will attempt to map non-geographic data, such as plotting "iOS" in Greece). Visualizations can be filtered interactively to look at just some columns or only records that meet certain criteria. The graphics let readers see data points when mousing over bars/points/pie slices. And, they can now be used on non-Silk sites such as:
Drawbacks: While you can customize the data that appears, there's no customization of colors or even chart headlines. The graphical interface takes a little time to get used to -- for example, I inadvertently created a new blank page in my collection when clicking on a dropdown menu I thought would let me navigate between pages in the collection. Maps don't include legends.
Skill level: Beginner.
Runs on: Any modern Web browser.
Learn more: See the Silk tutorials page.
Bottom line: If you want to do serious data visualization and analysis, this platform isn't for you. If you need a quick way to create an embeddable chart, there are probably better choices. However, if you want a way to post and share information that combines structure and commentary, Silk may be worth considering.
Looking for more free data tools? See my chart of 30+ free tools for data visualization and analysis.