Brahma has a couple of temples today. Rudra (Siva) and Vishnu (counting his Avataras also) have hundreds if not thousands.
How about Indra, Agni, Soma, et al., and in particular Vayu, who has a high standing among Madhwists?
(Temples to Vayulinga like Kalahasti would count as temples to Siva.)
I'm not counting the immensely popular Durga, Kali, Hanuman, Murugan, Ganesa, et al as Rig Vedic Gods.
Indra: There are many, one of the bigger ones is in Bihar. Here is a 360 view of that one.
Agni: Again, there are quite a few- one modern-looking one is in Nashik Maharashtra, which you can see here.
Soma: I couldn't find any.
Vayu: He seems to have the most. One is in Mumbai, which you can find here, and here is a blurry photo of the temple itself.
Surya: There's a big, beautiful temple in Kandilpur. There are many photos here.
Brihaspati: He has a huge temple in Rajasthan, photos here.
Yama: He also has a big temple, found in Telangana, photos here.
Mitra: I couldn't find any.
Varuna: There is the Varuna Bahvan Kovil in South India, photos here.
Ushas: None found.
Ashvini: There is the Ashwini Kumarau Mandir, photos here.
Thus, with the exception of Soma, Mitra, and Ushas, many of the other traditions are still alive and well.
