The invention in some embodiments features a contextual content delivery system (CCDS) for enhancing conventional web content with pop-up bubbles that display information when a cursor hovers over a word, link, or icon. The CCDS is configured to identify words or links in a document, determine their context, select the appropriate bubble from a plural of bubble types for each of the words or links, select content for each bubble based, in part, on the context in which the words and hyperlinks are used. The context can be determined from various sources including the resource in which the word or link appears and the target resource to which the link points. Thereafter, the CCDS enhances the words or links so that bubbles are automatically invoked in response to the appropriate trigger.