Okay, I took you at your word and didn't hesitate. *g*
Some of this may well already be under consideration, but here's my first-and-second impression after clicking around a bit:
-- I really like having an overview of all the recently updated forum posts in reverse chronological order, *much* handier than skimming down the forum for individual updating dates. I'd been hoping for something like this! Love it. Even more awesomesauce would be if it showed when an Unread post was made. (EDIT: A tab 'Subscribed posts' could also be interesting, in addition to the 'Unread subscribed posts', making it easier to find stuff again I was interested in.)
-- Ditto games. Here, for me even more customization would be great, as I play some games but others not at all; for me it would be even cooler if I could see, say, the last three recently updated Shiritori games but could choose not to have the Haiku game on my dashboard, since I don't play that. (Though I realise this is at odds with your aim of getting people to try out new things. Still, I'd looove being able to see more than one recent Shiritori, perhaps again with update dates.)
-- Love the Most missed top 10 box. (A link to the term center around there might be useful too?)
-- There is a spelling error in "The newest version of renshuu.org's mobile site is now avaialble!"
-- Would love the option to have a one-click way to get to the quizzing settings right from the dashboard. I could just have missed a more sensible way of doing it, but right now I reach the general settings by clicking on one schedule, then on that schedule's settings, and then on general settings. And then I never really remember how I did it.
-- Visually I think it could be good to have the profile pic on the dashboard too, even though it's a dashboard of 'stuff to do' not a personal profile.
-- I'd love for the grammar practice/grammar library to show up on the dashboard as its own box. For me personally, it would even be ideal if such a box showed where I last 'stopped'; I'm working through the grammar practice in a fairly linear way and having a direct link to the 'next' grammar item/expression would be cool.
[On working through the grammar library, I have a general point that probably doesn't touch upon the dashboard design, but while I'm here: as I said, I'm working through the grammar items in a fairly linear way, using the JLPT grammar. But I find the way I have to click around to get back to my grammar set (grammar set as in, 'the N5 grammar') after filling in sentences for expressions a bit counterintuitive. I would find a 'main page' with perhaps visual indicators (sometimes my brain likes things very simple and in bright colours *g*) for the grammar of one group (like 'N5') that I can go back to when I've written sentences handier and more tidy than the drop-down menu on the Grammar Library page.]
I really like the dashboard in general, I think it will be extremely useful!