I have just added three links for ukulele oriented forums that I visit with some frequency. You may have others, and if so, let me know and they can be added. These forums are free of cost, but you can make a contribution to assist them in keeping their operations going.
Ukulele Underground is a large forum based out of Hawaii and it contains a lot of material. There are new lessons posted each month and the principal in the group also hosts on-line courses. The forum section contains sections for beginners, a general section called Uke Talk, one dealing with regional subjects (like upcoming shows and festivals) and so forth. This is a very popular site with lots of members and activity.
The Flea Market Music site is also very popular with thousands of members. The Bulletin Board section has ;posts in all uke subjects and the Marketplace section is unique in that it has photos of ukes that folks want to sell. (Many folks post items for sale here before putting them on Ebay.). The Collectors section is unique in that the moderator of that section is an expert on historical ukes and can identify ukes like my otherwise unmarked 1928 Gretch banjo uke w/o any difficulty. This forum is run by Liz and Jim Beloff, early proponents of the uke and publishers of all the Jimpin Jim music books, the 365 Daily song book. The family makes and sells the Flea and Flukes (made in the USA!)
Ukulele Cosmos is based out of the UK and much of their material is related to European, and in particular British interests. One of their subsections deals with banjo ukes, something not well covered in the US forums.
Warning: browsing these can take a lot of time!