We maintain a list of volunteer opportunities within the EA movement, which any individual or organization can edit and add to. Look through the list of all projects here and find one that you takes your fancy - or add your own.
Tom AHosting, help & money for volunteer EA projects
Substantial tech work - building a whole website or service for you (this is reserved for the highest impact projects, as we're a lean organisation with limited capacity and an approach of only spending substantial money - as opposed to money for domain names, etc. - on projects which fit our own impact mission).