Are there more pen tablets other than Wacom?
Yes, quite a few. However, always be very careful with other brands. No-name brands grossly lack in accuracy and precision, and some have tethered pens which truly limits freedom of movement. Some other brands like Adesso, Aiptek, DigiPro, Genius, Pablo, Trust, UC Logic, … are a little less expensive than Wacom’s newest line of drawing tablets (Intuos4), BUT they do not have battery-free pens. This means that the pens are heavier and thicker plus you will always need to replace batteries which can prove to be very inconvenient and expensive in the long run. With less-expensive drawing tablets, unfortunately, you often get what you pay for: lagging problems, jittery controls, lack of precision and inconsistent lines, many pressure sensitivity issues, quirks in mapping the monitor to the tablet, pen freezing up, erratic pen performances, poor construction, software/driver errors, unreliable and unpredictable results, incompatibility with Windows or Mac, unprofessional quality, not user