Tiger, I'm glad the idea of usefulness works for you. I have a little (yes, it's little, but I'm hoping you guys can add to it) list of things we (and our culture/the general public etc) usually say and think, and some ideas for what might be more, well, more useful!
Some of the usual questions we "ask" ourselves: Is it rational? Is it stupid? Is it correct? Is it perfect? Am I an idiot for thinking it? What will people think of me for thinking it? Will I be considered "stupid" if I think this?
Some ideas for more constructive/useful things to pose to ourselves: What does this thought mean to me? How does it feel when I think this? Is this belief helpful or harmful to me? Is this thought based on evidence or is it something I made up out of anxiety (is it a "what if")? Are there any alternatives to what I'm thinking right this moment- any other perspectives? Is my thought rigid and perfectionistic- not open to any feedback or exploration- or is it flexible?
These are just what came to mind this morning. But hopefully you can see what a difference what we ask ourselves makes (and how we think about what we're asking - since so much of what we say to ourselves is loaded with particular (usually negative) connotations).
When we choose questions from the first list there's little chance for exploration. We're more concerned with "are we doing it right" than what it all means to us. The first list easily becomes rigid. The second has a chance to let us explore ourselves and learn more about who we are and how we work.
There's two levels here- there's what we as individuals tell ourselves- and we know people who suffer from eating disorders tend to tell themselves pretty negative things- but there's also the cultural level. Think about how many times on TV or in movies or on the street or at work or school, you've heard people say things from that first list. Our culture would do well to focus more on the second list. It's not our usual style- as a culture we can be pretty judgmental about what we think and feel (and, there are some pretty cool things about our culture too... there's just always room for improvement :)