There are these websites that have raw data feed going on. I'm scraping those data, process them and present in a digest-able format to user, and charge users for viewing it.
What will actually happen is the user will go to a certain page from a website that I don't own, click the bookmarklet that I provide, which will inject a script to scrape data, process open up a popup or a floating modal window right in that page and display processed data.
Is that OK or not?
It depends on the terms and conditions of each individual site, as scraping may be called out as a forbidden activity. It sounds like you are providing a data manipulation tool rather than a tradtional scrapper (scrappers normally run automatically from one or more machines and pull the data to a central place) as your requests are orginating from the distinct IP of the user which will receive the data. If the extractor actually requests from your server IP rather from the users machine you will likely be spotted and have your IP address banned.
If the site owner does not specifically forbid data extraction in the ts and cs, you should be ok, but be wary of how much data you pull as anyone who pays attention to data usage on a site might change the format of getting at the data.
What you have described (a) likely will constitute copyright infringement in many instances and (b) may violate terms of service in some instances, so the answer is "No, it's not [legally] OK."
Disclaimer: This information does not constitute legal advice and does not establish an attorney-client relationship.