A few companies of interest:
StrikeIron -- Aggregates and standardizes data: perfect for map mashups
Viddler -- Rich video: allows tagging, comments and more. If it works, it's clearly the next step.
Brightcove -- Provides video infrastructure now also a destination in its own right
SocialText -- Wiki for enterprises
NetVibes -- Website customization is prohibitively expensive. NetVibes makes it cheap
Omnidrive -- The difference with this web storage is you can build it into your own site