The most pleasing addition to the list of newspaper archives for 1901-1950 is the Spectator, the most influential conservative weekly of the period. The Spectator archive is free; near-complete from 1828 to 2008; contains both images and text — and the OCR is high quality; tagged; and is easy to search or browse. However, there is no advanced search function (though you can use Boolean operators such as AND and NOT). While you can use the Trove-style filters to narrow a keyword search down to a decade of interest, you can't zoom into a year, let alone a month, week or day. There doesn't seem to be any easy way to save article images (the best way I've found is to zoom on the page and use the web browser to save as HTML; you get a lot of extra junk but among them are two usable images). And it's a shame that illustration captions and advertisements appear to have been excluded from the text search, though they are visible visually. Still, it's all still in beta, and did I mention that it's free?
Welsh Newspapers Online is expanding rapidly, having added the following titles:
Cambrian News and Merionethshire Standard
Cymro A'r Celt Llundain
Montgomeryshire Express and Radnor Times
North Wales Express
North Wales Weekly News
Rhyl Record and Advertiser
South Wales Daily Post
Weekly News and Visitors' Chronicle For Colwyn Bay
The coverage for most of these ends in 1910, as with most of WNO's titles; however, Cymro (published in Liverpool), Aberdare Leader, Cambrian News and Merionethshire Standard, Lials Llafur, and Merthyr Pioneer all cover at least the period 1914-1919. The war will be mentioned.