Talking about the weird and the wonderful (see post on aristolochia below), the other two which undeniably fall into this category are the Rafflesia and the Titan Arum (Amorphophallus titanum) of the Araceae family.
The name "corpse flower" has been applied to both because both reek of rotting flesh and both happen to have extremely large flowers. Incidentally, both can also be found on the Island of Sumatra. The Rafflesia is considered to be the world's largest flower. The Titan Arum on the other hand is the world's largest unbranched inflorescence. The Tailpot Palm (Corypha umbraculifera forms the largest branched inflorescence. Here are write-ups I found on Wikipedia.
Amorphophallus titanum or Titan Arum, is a tuberous plant endemic to western Sumatra, where it grows in openings in rainforest on limestone hills. Locals know it by the more evocative name 'corpse flower' (bunga bangkai), because of the hideous stench the fly-pollinated inflorescences produce. Mature tubers of A. titanum typically weigh between 25 and 50 kg, with weights up to 75 kg recorded. Tubers produce solitary, highly dissected leaves over 3 m high and 4 m across. Leaves persist for ca. 1-2 years. The plant enters a dormant phase of several months after a leaf senesces, before sending up a replacement leaf and growing a new root system. Leaves are hysteranthous: flowers are borne by otherwise dormant plants. The timing of dormancy and growth phases seems to be more or less random with respect to the seasons; wild populations are reported to have plants in various stages of growth at any given time. It is unclear why the plants ever go dormant at all, given their equatorial habitat.
Flower buds emerge shortly after tubers become dormant, and are accompanied by the development of a limited root system, unlike the flowers of temperate Amorphophallus species. Inflorescences consist of a fluted spathe (petal-like leaf) with a meat-like purple interior, and a sickly-yellow spadix (central stem bearing many small male and female flowers). While technically not single flowers, the inflorescences of A. titanum are the largest flower-like structures in the plant kingdom, often reaching 2 m high and 1 m in diameter, or larger. While open, the spadix warms itself with metabolic heat, in what is perhaps an adaptation to volatilize and disperse its carrion-insect-attracting odor. The putrid smell of the corpse flower is strongest just after the spathe unfurls, late at night, suggesting pollination by nocturnal flies and beetles.
Rafflesia is a genus of parasitic flowering plants. It was discovered in the Indonesian rain forest by an Indonesian guide working for Dr. Joseph Arnold in 1818, and named after Sir Thomas Stamford Raffles, the leader of the expedition. It contains approximately 27 species (including four incompletely characterized species as recognized by Meijer 1997), all found in southeastern Asia, on the Malay Peninsula, Borneo, Sumatra, and the Philippines. The plant has no stems, leaves or true roots. It is an endoparasite of vines in the genus Tetrastigma (Vitaceae), spreading its root-like haustoria inside the tissue of the vine. The only part of the plant that can be seen outside the host vine is the five-petaled flower. In some species, such as Rafflesia arnoldii, the flower may be over 100 centimetres (39 in) in diameter, and weigh up to 10 kilograms (22 lb). Even the smallest species, R. manillana, has 20 cm diameter flowers. The flowers look and smell like rotting flesh, hence its local names which translate to "corpse flower" or "meat flower" (but see below). The vile smell that the flower gives off attracts insects such as flies and carrion beetles, which transport pollen from male to female flowers. Little is known about seed dispersal. However, tree shrews and other forest mammals apparently eat the fruits and disperse the seeds. Rafflesia is an official state flower of Indonesia, also Sabah state in Malaysia, as well as for the Surat Thani Province, Thailand.