There are portable keyboards in the market today, but many are not easy to transport because they are fixed in size making them less than desirable to transport. And most are based on a physical connector to the computer. With the growing world of tablets, we need to rely on Bluetooth keyboards, but getting them in a very portal product is slowly coming to market. Silicon keyboards let you roll them up for transport and since they are silicon, they are very easy to clean. The problems to this point is prices for these which you would want. Plan on paying over $50.
But, I am starting to find them under $50 and may make them even lower over time. The most recent find was over at Brookstone for $49.99. It is available in black, blue, green and pink for you selection and is designed to connect up to tablets via a Bluetooth connection. Given that this can roll up to a compact size, it should be an easy item to consider taking with you.
Weighing in at only 5 ounces, this is not going to be adding to your overall weigh very much. Part of this is the battery which can be charge via a USB connection. The rating on this is to provide up to 90 minutes of use before it has to be charged again. And it uses Bluetooth 3.0, so newer tablets should have no problems working with this one.