There are several tools available that will make your life easier by automating the requirement management process. In the end, they can't do the job for you - as seen, the tasks are complex and require high level of abstraction and analytical thinking. But these tools can keep track of things where human memory fails, and can perform the steps that need to be repeated.

To begin with, a database which provides proper access to all members of the development team is by far a better solution that passing around post-its in the office. So, such a tool should facilitate communication, with the office colleagues as well as with overseas department. Also, it should keep things organized, and allow you to identify a certain requirement and trace it back to its origins, even after having worked on the project for five years. It should also store how many changes has one requirement suffered, who initiated the changes, who approved them, when did this happen, and who performed the analysis of the impact the change would have on the entire system.

Some tools are less sophisticated than others, but still considerably useful - such as the old checklists. You will find many templates available on the Internet, you can start by using any of them and refine and adapt them to your needs. You don't know if you can actually use them, until you try. You can also see how the requirements management is integrated in the project management software you are already using.

There are also several products designed specifically for requirement management, such as RTM Workshop and Caliber-RM. They include a database with custom-defined accessibility access, and can be easily integrated with other tools (such as importing a Word document, since you'll do a lot of text writing, or combining with a project management software). They are quite intuitive and easy to use, and have some powerful features, such as underlining "suspect" requirements and defining traceability options.

They can be helpful, but they won't do the job for you, particularly where highly conceptualized and abstract thinking is necessary.