• Data. We've been collecting data to learn more about the Tor network: how many relays and clients there are in the network, what capabilities they have, how fast the network is, how many clients are connecting via bridges, what traffic exits the network, etc. We are also developing tools to process these huge data archives and come up with useful statistics. Let us know what other information you'd like to see, and we can work with you to help make sure it gets collected safely and robustly.
• Analysis. If you're investigating Tor, or solving a Tor-related problem, please talk to us somewhere along the way — the earlier the better. These days we review too many conference paper submissions that make bad assumptions and end up solving the wrong problem. Since the Tor protocol and the Tor network are both moving targets, measuring things without understanding what's going on behind the scenes is going to result in bad conclusions. In particular, different groups often unwittingly run a variety of experiments in parallel, and at the same time we're constantly modifying the design to try new approaches. If you let us know what you're doing and what you're trying to learn, we can help you understand what other variables to expect and how to interpret your results.
• Measurement and attack tools. We're building a repository of tools that can be used to measure, analyze, or perform attacks on Tor. Many research groups end up needing to do similar measurements (for example, change the Tor design in some way and then see if latency improves), and we hope to help everybody standardize on a few tools and then make them really good. Also, while there are some really neat Tor attacks that people have published about, it's hard to track down a copy of the code they used. Let us know if you have new tools we should list, or improvements to the existing ones. The more the better, at this stage.
• We need defenses too — not just attacks. Most researchers find it easy and fun to come up with novel attacks on anonymity systems. We've seen this result lately in terms of improved congestion attacks, attacks based on remotely measuring latency or throughput, and so on. Knowing how things can go wrong is important, and we recognize that the incentives in academia aren't aligned with spending energy on designing defenses, but it sure would be great to get more attention to how to address the attacks. We'd love to help brainstorm about how to make Tor better. As a bonus, your paper might even end up with a stronger "countermeasures" section.
• In-person help. If you're doing interesting and important Tor research and need help understanding how the Tor network or design works, interpreting your data, crafting your experiments, etc, we can send a Tor researcher to your doorstep. As you might expect, we don't have a lot of free time; but making sure that research is done in a way that's useful to us is really important. So let us know, and we'll work something out.

If you're interested in anonymity research, you must make it to the Privacy Enhancing Technologies Symposium. Everybody who's anybody in the anonymity research world will be there. Stipends are generally available for people whose presence will benefit the community.

To get up to speed on anonymity research, read these papers (especially the ones in boxes). We also keep a list of Tor Tech Reports that are (co-)authored by Tor developers.