This may be moot - Since Google doesn't "Officially" used meta tags to rank your site - but that does not mean that key-words are useless - They continue to drive traffic to your site.... the most basic of comparisons would be against a forum with zero keywords to categorize it... The one with meta tags will place much higher than the other, unless the other has every "bell and whistle" possible to place it higher - Key words are still useful (imo) - that's just Googles 'unofficial' declaration.
a Quote from the site below (google support) helps explain the function (not how to use them, I assume the webmasters here understand deeper).
Meta tags are a great way for webmasters to provide search engines with information about their sites. Meta tags can be used to provide information to all sorts of clients, and each system processes only the meta tags they understand and ignores the rest.
As above - it doesn't necessarily help rank a site, but categorize them by "most helpful description", which imo may as well be site ranking. The difference here, in the old days you could have a crappy web site with an excellent array of key words which would help it go to the top of the page pile; Nowadays it takes more than key-words - but they continue to be a factor in rank albeit they are weighted in a lower capacity.
Sorry got a little off track -
My idea here is to create a fun little contest maybe rewarding some points, where members could submit a word or three in an effort to have it voted into the (...<meta></meta>...)
So that's the idea; another, "What do you think?" moment.