I recently saw a spiritual TV episode on Sundara Kanda and in that the host said that prior to Sita, Ravana kidnapped 25 or so women (I can't recollect the exact number).
Is this true? Could someone help me with a citation?
According to Uttara Kanda of Ramayana, Ravana kidnapped many other women, although there is no exact number to them.
While thus returning the vicious-souled Ravana, with delight, carried away stealthily, on his way, the daughters of the royal saints, celestials and Danavas. And whatever beautiful damsel he saw, married or unmarried, that demon held them captive in his car, having slain all their friends and relatives. In this wise he got on his chariot many a female of the Nagas, Rakshas, Asuras, Yakshas, Danavas and of men. And they, all afflicted, shed tears, hot as firey flames, caused by fear and fire of grief. As the ocean is filled with the currents of the rivers so that car was flooded with their tears originating from fear and sorrow. And wept there in the chariot, hundreds of the females of Nagas, Gandharvas, of great ascetics,Daityas and of Danavas. They had long airs, graceful persons, countenances resembling the full-moon, rising breast, slender waist like that of a black-bee and were graceful with back like the pole of a car. They were like the females of the celestials and the burning gold and were all afflicted by grief, sorrow and terror and were young. And the car was ablaze on all sides with the sighings of those damsels and Pushpaka looked like the chamber where fire u kept perpetually. The countenance and eyes, of those beautiful damsels, brought under the subjection of the tennecked .demon, and afflicted with sorrow, looked poorly like a hind attacked by a lion. Some thought—"Will he eat rac up" and another, stricken with sorrow, thought—"Will he destroy me?" Thus remembering their mothers, fathers, husbands and brothers, all those females, overwhelmed with grief and sorrow, bewailed, some exclaiming — "What shall befall my son in my absence? Alas! into what ocean of grief my mother or brother is sunk? Alas ! what shall my husband do in my absence ? Therefore, O death, I propitiate thee, do thou take me, who am subject to miseries. Alas ! what an iniquity did I perpetrate in my former birth in my another body ? Therefore, we all, overwhelmed with grief, are sunk in the ocean of sorrow — and I do not behold the of my miseries. Oh ! fie upon humanity ; there is none more vile than a man for they are weak. As the stars disappear with the rising of the sun in time, so our husbands have been destroyed by the powerful Ravana. Oh ! highly powerful is this Raksha and he is mad after devising the means of destruction. Alas ! being engaged in such vile actions, he does not consider himself cursed ; he is as powerful as he is vicious. And though the ravishment of another's wife is a great sin, still that vile Rakshasa is enjoying us who belong to others. Therefore this vicious-minded one shall meet with death, by his own actions."
During the same rampage, Ravana accidentally kills Surpanakha's husband too so he sends her off to live in the Dandaka forest under the protection of Khara and Dushana.
Do thou ever reside by the side of thy rich brother Khara and he shall be the lord of fourteen thousand Rakshasas. That highly powerful one shall give food and clothes to all those Rakshasas. He is thy cousin and that night-ranger shall always carry out thy orders. Let that hero now speedily go to protect the Dandaka forest and the highly powerful Dushana shall be the commander of his forces.
And the heroic Khara shall always obey thy words and be the lord of Rakshasas assuming shapes at will." Having said this the Ten-necked demon issued orders to his army—fourteen thousand highly powerful Rakshasas. Being encircled by those grim-visaged Rakshasas, Khara, undaunted, speedily came to the Dandaka forest. There he governed without thorns and Surpanakha too also resided in the forest of Dandaka.
Ravana was the worst villain of his time. He had raped/ molested many women.
Ravana had raped Rambha, the daughter-in-law of Kubera [Ref: Mahabharata 3.278]. Ravana had molested Rishi Kushadhwaja’s daughter Vedavati in Naimisha-vana (grove) near Kurukshetra in present-day Harayana state [Ref: Ramayana 7.17].
Ravana had molested Dvaipayana's sister, dragged Atri's wife by her hair, raped Rtuvarman's wife Madanamanjari, humiliated Agni's wife Svaha, tried kidnapping Brihaspati's daughter Sulekha, and tried humiliating God Brahma's daughter Punjika [Ref: Puranic Encyclopedia page 646].
As per folklore, Ravana had also raped Rishi Udanga’s daughter Malati on the banks of River Godavari.
Ravana had even cast his evil eye on Goddess Lakshmi in the higher regions. He was dumped back on Earth by God Vishnu, as he remained protected by God Brahma’s boon [Ref: Ramayana 7.28].
Source: 'Essence of the Fifth Veda' by Gaurang Damani pages 15-16
I do not know exactly how many women were kidnapped by Ravana, apart from Sita. However, He kidnapped Takshaka's wife. This incident is mentioned in Valmiki Ramayana, Aranyakanda.
After Rama defeated and killed Khara, Dushana, Trisira and 14,000 Rakshasas in Janasthana (inside the Dandaka forest), Surpanakha went to Lanka and told about the incident to Ravana. That time, when Surpanakha entered Ravana's palace, a long description of Ravana's power and deeds was given by Valmiki. In this context, the following thing is mentioned-
the destroyer of righteousness, and the violater of other's wives;—the employer of all celestial arms, and the disturber of sacrifices;—who going to the city of Bhagab* and vanquishing Vāsaki, had carried off Takshaka's beloved wife. - Ramayana III.32.12-14
*The city of Bhagab is Bhogavati.
The verse number is taken from the Bengali translation of Valmiki Ramayana by Panchanan Tarkaratna, which comes with original verses along with verse numbers.