This isn't a decompression bomb, but here are some fun virtual disk images I found using AFL fuzzer. One of the files is 329 bytes, but causes qemu to consume 4 GB of heap trying to process it. This has interesting consequences for the public cloud, where people can upload any old stuff and it is usually processed immediately by 'qemu-img'.

https://bugs.launchpad.net/qemu/+bug/1462949

(I have a big collection of these, but most of the bugs have now been fixed in qemu)