The SeaMonkey Project is constantly in need of developers, testers, marketers and other contributors to our success. If you want to help, you can find some resources here.
Our Getting Involved with SeaMonkey page is another good entry point to helping out our project, as well as the SeaMonkey pages on the Mozilla wiki - and the SeaMonkey blog features development news every now and then.
As we're part of the Mozilla project, most of the mozilla.org developer pages also apply to SeaMonkey, there's also content there that explains how to get the comm-central source code, which includes the current SeaMonkey development code.
For getting into contact with the SeaMonkey development community, for example if you want to help us and have questions, try the development group/list and IRC chat as listed on the community page.
The SeaMonkey project and source code is divided into several areas, we have a list of SeaMonkey project areas available that also contains people ("owners" and "peers") responsible for those.
If you have already submitted patches to Bugzilla, you might be interested in our review and flag policies that apply to such patches.
The Mozilla tinderbox service also has information on the current tree status 24 hours a day.
You can help make SeaMonkey available in your language! This process not only involves translating text but also adapting resources to fit for people in your local environment, which is why we call it "localization", often abbreviated to "L10n" (an "L", 10 other characters, then an "n"). Get more information about how to help with this on our SeaMonkey Localization wiki page.
Testing our code is a very major and important task in every software project, and the good thing is that anyone can participate in that by downloading "Nightly" builds, using them and reporting bugs.
"Nightly" builds are versions of our software that are made every night from the
most current source code, the most experimental and dynamically changed
versions are from the so-called "trunk" of the development tree, available as
trunk nightly builds. Those are the versions that need the
highest amount of testing, often contain exciting new features but also can
easily crash or destroy any of your data (some people claim they can also eat
children or make your kitchen go up in flames, but we have no actual evidence of
such things actually happening - yet).
To cut things short, we're happy about everyone testing those builds, but
be very careful and keep backups of your data if you do so, as some of the
code you're testing might not have been tested at all before.
"Aurora" builds are versions of our software that are made
every night from a source code point in a stabilizing state. Those versions
that need a lot of testing but are more stable than the "nightly" builds.
If you want to help testing but "nightly" builds are too risky for you,
we'd be happy if you help us test those.
Our Getting Involved page, the Mozilla wiki on SeaMonkey QA (Quality Assurance) and the MDC (Mozilla Developer Center) QA section offer some good additional info about testing and helping us improve our software quality through that.
Even as a normal user of stable SeaMonkey versions, you can help the project a lot by spreading the word and telling all your fellow friends, web developers and other people around you about our great software.
You can use our logo & artwork for pointing other people to SeaMonkey, as that is explicitly allowed by our SeaMonkey trademark policy.
The merchandise available from the SeaMonkey shop can also help you in spreading the word.
And, last not least, you can donate money to the SeaMonkey project via our host organization, the Mozilla Foundation.