I've recently encountered comics in CBT format. Based on what I found online about the format it's newer and is "the *.cbt files are basically renamed TAR archives and can be decompressed with any TAR file utility." Similar to how CBZ are renamed ZIP archives and CBR being RAR archives. It would be nice if support for this format was available in the near future because it looks like CBT files are about half the size of CBR or CBZ files yet maintain the majority of the quality.
Here is a link to a site with more detailed info on CBT files, if anyone is interested.
www.file-extensions.org/cbt-file-extension
Also now that I can get DRM free files straight from Comixology in either CBZ or PDF format I would like to see YAC support PDF's. I have a number of eBooks also in PDF format that I could use YAC Reader for and be able to ditch one of the other readers I have on my iPad.
Regardless of PDF support this is by far the best reader I've used for my iPad. I have a friend who has a Kindle and he's always getting new/different readers because he hasn't found one that compares to YAC. It would be cool if this came out on Kindle but I imagine there is a bit more involved to be able to be featured in their store, as they have the smallest storefront of apps out of any Tablet OS.