Calligraphy is one of the most known of Chinese art forms, and as it can come in all shapes and sizes it makes an excellent gift item.
The traditional form of calligraphy for display or as a gift is a scroll, often with the painting actually on a silk base.
However these days the most common calligraphy item for purchase is the greeting-card sized "Your name in Chinese" cards which are available from many shops in Stanley Market.
Each card consists of two or three large Chinese characters in traditional calligraphy format representing a name. As these are for sale to tourists they represent "English" names such as John or Mary.
Of course there are not really any Chinese words for these English names -- however a common usage has evolved for particular Chinese words to be used to represent particular English words, either based on the sound or the meaning.
Occasionally you will also see for sale "Rainbow calligraphy" which is Chinese calligraphy done with multicolored inks. These are strictly for the tourists and rather frowned upon by the serious collector of calligraphy.