Just installed Mollom on the site - more to see how it works so that I can set it up for a client site. It looks like a really good module and integrates nicely into Drupal, although when its co-created by Drupal founder Dries Buytaert you'd kinda expect that!

On initial inspection it seems very similar to Akismet which was aimed very much at Wordpress (although has a Drupal module which is reportedly no longer supported as of Sept 2008).
One nice feature of Mollom is the automatic inclusion of CAPTCHA's which is something that Akismet didn't include last time I used it. I can see this really helping to reduce the burden on site admins to have to approve or reject false positives which were highlighted by the system since the CAPTCHA should add that extra level of verification should a post be initially flagged as spam.

The second thing i've installed this evening is Panels 2. I've never really explored this module before but I really wish i'd seen it earlier. You can do some really cool things with the layout and positioning of content , giving that extra degree of flexibility you don't get with views or blocks.

So all in all, some interesting modules to play with there any try to re-write my website (In this none existant spare time that I have!).