So you've spent a few weeks or months planning out your research community, including defining your objectives, drawing up your facilitation plan, seeding your site, screening participants, etc...  Launch day comes and goes, and things go off without a hitch.  Your research participants start signing in, introducing themselves to you and other members and participating in early research activities.  Life is good.  

A few days later you start to notice that the initial buzz and excitement is beginning to die down a bit, so you check the stats.  People are still signing in, but it seems a bit different somehow than the "honeymoon" right after launch date... 

No worries, this is completely normal for a community launch and nothing to be too concerned about (yet).  The "lull" right after launch is bound to happen.  The key is to make sure it doesn't stay, and that the community builds into something sustainable, with regular participation from a broad cross-section of members.  Here are a few tips to help you get your MROC off on the right foot... 

1. Throw a few "softball" activities out there - Try throwing out a few "softball" activities at first.  Think of the types of questions you would ask in the first five or ten minutes of a focus group when you're building rapport with the group...  Those are the perfect questions to start with in an online research community.  They're personal and fun, without being too deep.  Every moderator has their own bag of tricks that will probably work just as well in the online environment, so why not try them out to see what works best...
2. Try out some surveys - Also try starting with a few surveys or polls that may or may not be related to the topic, and be sure share or discuss the results with members.  Surveys are easy to fill out and provide a quick engagement point for members that are just getting their feet wet in the community.
3. Email them more at first (and regularly) - In the first few weeks, be sure to setup a regular schedule for emailing participants about community news and updates.  We like to email all of our communities every Tuesday with news and reminders that the latest research activities are available.  As long as you're fairly routine in your communications (and set this precedent early), you'll be assured of regular participation among a core set of members.
4. Get personal (on their profile pages) - We like to add a welcome message to member profile pages initially, and then find any excuse we can to follow-up with additional messages.  That lets members know you're paying attention and sets up an expectation for reciprocation. 
   

Those are just some tips that have worked for us in the past.  Feel free to share any ones that have worked for you in the comments to this post!