Can I add small apps that my users can utilize

I am starting a new member based content and tool website based on WordPress and I have a general question. I would like to give my users paid access to some special tools, can I use WordPress extensions for this? Do I need to have custom programming? Any suggestions for tools, where to search, ect.,

For example, I want my members to have a web-based project management tool? And I want a custom feed from some other sites developed for each member and sent to their email.

I am just not sure where to start.
Any guidance as to where to start would be greatly appreciated!!