Maybe Geckoboard will add support for Twitter images . . .
Until then I started looking for some 'clean' (no pics, videos, retweets, etc.) twitter accounts to use as a random fact widget.
It was very difficult to find clean twitter accounts.
With simple search operators (via Follow the Hashtag) I was able to get what I was aiming for.
Used: from:chuck_facts OR from:@nasa OR from:@factsoup AND -rt AND -filter:media AND -filter:links
Will continue to tweak if I can find another feed like @factsoup.