How about for world peace (seriously)?
I'd think that that would be a biggie.
Or praying for general guidance.
I was listening to Prairie Home Companion yesterday, and Keillor interviewed Satan (Beelzebub, or just "Bubba", please) for a few minutes. When Bubba threatened to sic a puma on him, Keillor said he could pray for divine intervention, and that Bubba would be powerless against God's Divine Will. Bubba replied [paraphrasing] "Just like you've prayed for world peace all these years? Yeah, like that one ever worked..."
Dead silence in the hall. They waited a few beats, as if they were expecting that line to have gotten a laugh, and moved on.
Seriously? I do not pray, but I use various different things as reminders. That is, for instance, I will wish on the first star. I have no illusions that it makes any difference, but I think "if it did make a difference, and you only got this one wish (unlike a prayer, where you can make as many as you have time for), what is so important that I would use this one wish on it?" I figure if there is something that important, then I would like to remind myself of it on such occasions. If it is something I can work toward, a reminder can prompt me to do something. If it is not, perhaps it can get me thinking of a way to make it something I can work for. For the past X amount of time, it has been a wish for good health and happiness to a friend of mine who suffers from depression. I try also to regularly do other things--the wish does not take the place of real action. (To me, one of the things that irritates is the "moment of silence" that allows people to think they have done their bit, when in fact they have just wasted a moment.)