Though not expected on the market before early next year, FrogPad, developed by Houston-based FrogPad L.L.C., could revolutionize the exploding market for wireless Web technology. While the gadgets -- smart phones, handheld PCs and personal digital assistants, like the Palm -- are getting smaller and more sophisticated, manufacturers have yet to figure out how to incorporate a practical, easy-to-use keypad that allows the full range of letters and numbers to be entered. Smaller than a pocket paperback, the FrogPad offers the same functions as the traditional 104-key "Qwerty" keyboard, but with only 19 keys. The secret is in the location of keys for the 15 letters used most frequently, which, combined with four secondary keys, allows for easy one-handed use. FrogPad is relatively effortless to master: Users can learn how to type 40 words per minute in ten hours, compared to the 56 hours it takes on a traditional keyboard. The first widespread use of FrogPad likely will be on cellular phones. Inventor Kenzo Tsubai and his partner, Linda Marroquin, recently met in Helsinki with representatives from Nokia, whose strategy, according to its 1999 annual report, is to combine mobile phones and PCs into a single "personal communication tool."