I agree with you! It's always good to have "bite-size" materials
I don't really know any good websites of comics, but it might be a good idea to look for manga with 4 sceans (4 koma manga).
4-koma manga has 4 boxes of images with short (complete) story in it. It's usually a humourous.
I tried to search online, but it might be difficult to find one with furigana.
Hope this little info will help you a bit.