I'm noticing a bunch of 0 Eth transactions spamming the EOS Crowdsale contract. They all seem to be coming from smart contracts that have already bid into a block. There's no telling if these are just badly written smart contracts or if there's some intentional effort to spam the EOS crowdsale. Thus far, the EOS ICO has really slowed down after raising ~$180m in the first days.
There hasn't been any announcements of network congestion yet but it's definitely something to keep an eye on if you're trading Eth or EOS. The contract can be viewed here: https://etherscan.io/address/0xd0a6e6c54dbc68db5db3a091b171a77407ff7ccf
EDIT: As @altruist have mentioned in comments, many of these are transactional aspects of EOS at work. That explains things quite a bit!