Has anyone successfully used the Belkin 4-port F4U016 or the Belkin F4U040SA with the Pi? I need to power a Wifi dongle, keyboard and a pen drive. Any advice?
You can check the link goldilocks provided for the USB hubs. At least one of the USB hubs you've mentioned requires an additional power source. For the components that you have mentioned a powered hub may not be required. Depending on the Pi that you own you know how much power it can supply.
You can check this answer out to for information on permissible power limits. Depending on the type of keyboard, the power it requires will vary. Most basic keyboards work fine. You'll have to do the same drill for every device that you plan to connect to the Pi (basically check the power rating, add them up and see if the Pi can handle it). In case you're buying a hub to save on the USB ports then any approved hub from the link provided by goldilocks should do. Not sure if I've answered your question though!