FreedomPop, which offers 500MB of free wireless data service a month via Clearwire’s WiMAX service on a range of devices, has a better offer for tablet owners coming in the second half of this year.

The FreedomPop Clip is designed to attach to Wi-Fi only tablets and provides wireless Internet connectivity when away from Wi-Fi. Better still, the service will be free for the first 500MB of usage each month and will support Sprint’s up-and-coming 4G LTE network for faster browsing. The add-on hardware only weighs 2.5 ounces and has its own built-in rechargeable battery estimated to last up to six hours.

Tablets enabled with support for mobile data networks have never sold particularly well because of the added cost and expensive two-year contract required to maintain the service. Instead, some customers tether their tablets or enable an add-on Mobile Hotspot feature on their smartphone, which can cost $30 extra per month. The new FreedomPop Clip does not come with a contract or a monthly fee when users keep browsing to under 500MB each month. The forthcoming device will also support up to eight extra connections, in case you want to share.

Those who want more data, and around 30 percent of FreedomPop’s customers reportedly do, they can buy it on-demand without any contract or commitment. If you bug your friends to also buy the device, you can earn additional free browsing. In fact, FreedomPop will try and encourage sharing by including a new “open Wi-Fi” Internet service on a separate SSID. Those connecting through the open feature will likely get a marketing message encouraging them to get their own FreedomPop device, and their usage won’t count against your allowance.

FreedomPop Clip supports Sprint’s up and coming LTE 4G network.

Stop the Cap! has FreedomPop’s $99 iPod Touch add-on device, which works exclusively on Clearwire’s network. We’ve used it for about five months and can report the device works well whether you actually have an iPod or not. It is simply a portable hotspot shaped to clip to the back of the 4th generation iPod Touch (it won’t fit ours). But even if it cannot clip on, it still delivers excellent signals up to 12 feet away from the MP3 player.

Its biggest weakness is Clearwire’s hit or miss network. Here in suburban Rochester, N.Y., Clearwire provides service through a nearby cell tower about a mile away. At home, the device works with fair reception indoors, but really needs to be near a window to perform reliably. Outdoors, the device works much better. We found more trouble trying to use the device in a nearby restaurant and while in downtown Rochester because Clearwire reception proved spotty. When it does work, it provides an average of 800kbps-1Mbps downstream speeds, which is superior to most 3G networks, but does not come close to what Verizon’s LTE network can deliver. But then, FreedomPop data comes free.

Just remember to keep usage at 400MB or less every month. As you approach 500MB of usage, FreedomPop will “conveniently” bill you for additional usage it anticipates you will use unless you remember to shut this auto top-up feature off on FreedomPop’s website control panel. You must also use at least 5MB a month to keep the device active, so remember to power it up at least once a month and do some browsing.

The FreedomPop LTE-capable Clip will also reportedly work with 3G service, according to Forbes. This is an important consideration because Sprint’s 4G LTE network is still in its infancy and not yet available in most major metropolitan areas. But if it relies on Sprint’s overwhelmed 3G network, expect much slower performance.

The selling price for the device itself has not yet been announced, but we expect it will be available later this year at $99 or slightly higher.

Thanks to Stop the Cap! reader Jerry for sending this news tip.