Is there any plugin available to measure monthly active registered users?

I have been managing multiple domains/sites for my clients since a few years now and I think the easiest and best way to do it in your case would be setting up simple WordPress sites on each one of them and managing them with something like ManageWP(https://managewp.com/) . If they're niche domains, you can monetize them through ads or use them as affiliate sites. Selling them can also be also an option. If you can get the sites to look fairly nice and if they are niche domains, you can sell them on sites like Flippa(https://flippa.com/) . Overall, you have many options. I'd be glad to help you in detail through a call if you want.

Depending on the data, you can either use one of the following. Google Spreeshet / Charts: I use this for real time analytics generated from our system to quickly visualize the information. There's a simple JSON API that lets you pull that in although their is limits on the amount of rows you can use. Geckoboard: They provide dashboard type widgets you can configure to show you real time trends and information. Highcharts.com: Simple chart generator. We use this in our Admin Dashboard to visualize all our data include cohorts and weekly KPI's. I like simple and free.

Top 2 tactics: Existing Users and Industry Influencers. First, leverage the existing user base. Incent referrals with $5 for every new free user they get to sign up and start using PT Engine for a new domain. Second, reach influencers and offer them the same deal when they tweet / post to / email their audiences. Make the offer a 60 day free trial instead of the standard 30 day so that they are providing value to the people they refer as well. This is critical - don't make them feel sleazy, make them feel (and look) like heroes to the connections they share PT Engine with. That's $9k to get 1800 users, leaving you $1k for graphics, referral tracking system, administrative costs. I assume the $10k budget does not include your time - if it does you'll have to reduce the incentive, which will definitely make it less appealing. If you want to dive deep on reaching influencers, schedule a call with me at www.clarity.fm/ryandraving

There are some market-research companies which have very detailed sector specific knowledge. Thus, they are not freely available for consumers. Here are a few to get you started: http://www.mintel.com/ https://www.marketresearch.com/ https://www.marketresearchreports.com/ https://www.ibisworld.co.uk/

I am not exactly sure how Quora does it but I would guess that they use something like Google Analytics. It looks at what percentage of your visitors come back each day, every other day, each week, etc. It's a good metric system that is crucial for building a meaningful web product, and it's almost always positive. If someone comes back to your site regularly each week, or even better each day, it means you're becoming a regular and important part of their life. The problem with any other single metric system is they can be the result of positive or negatives changes to your product. You need to have a near-wholistic picture and Google Analytics can help with that. Tools like Klout and Hubspot are good with the measurement of engagement on a brands different channels (website, facebook, twitter, gplus...) too. Let's chat some more and get down to the heart of this problem. Hopefully I can help you resolve any internal discomfort around the matter.