Selected answers from the Dumb SEO Questions G+ community.
Travis Bailey: If you really wanted to, you could use Google Docs for most all of that. Basecamp would probably be a little more practical, for project management. You can even let the client see what goes on, in their project. That`s about $99 p/m. Trello might be another good option, but the devil is in the per user licence. Asana might be good as well, but it has a bit of a learning curve.
Dave Elliott: Do you mean SEO changes being made on a client site? if so, this isn`t bad https://www.contentkingapp.com/ if not...yeah, spreadsheet or trello
Linda Caplinger: Sounds to me like you`re looking for a project management tool?