Apart from the 18 major Puranas there are an equal number of Upa-puranas. Among them are the Vinayaka Purana and the Kalki Purana. There are also, in addition, a number of minor Puranas. The Puranas that speak of the glory of various months such as the Tula Purana, the Magha Purana and the Vaisakha Purana are parts included into the 18 major Puranas or Upa-puranas. There are also what are called Sthala Puranas, some of them part of the Puranas mentioned above and some existing independently. The puranas that sing the glory of the Kaveri and the Ganga exist both separately and as part of the major Puranas or of the Upa-puranas. In the Tula Purana, for instance, the importance of the Kaveri is the theme. It mention how auspicious it is to bathe in that river in the month of Tula (October-November).
If there are Puranas devoted to the deities there are also those dealing with devotees. The Tamil Periyapuranam tells the story of the 63 Saiva saints called Nayanmars. The same is available in the Sanskrit as Upamanyu Bhaktavilasa. Bhakta-Vijaya deals with poet-saints like Tukaram and Namadeva who were specially devoted to the deity Panduranga of Pandharpur.
For a general background, please see here