My personal feelings are that since there is not a history of/ongoing oppression of white people, that it does not carry much of a wallop and is not a term that disturbs me as much as other slurs that might be leveled at me. I favor not using slurs of any kind and would not recommend it to anyone, but also would not feel comfortable telling a PoC (especially online, on a personal site such as a blog) not to use that word or variations in expressing their frustrations. I don't consider it my place to insert myself into their experiences.
The word originated on the cotton fields when whites would "crack" the whip on the slaves working the fields, for whatever reason. So, really, when a black person is calling a white person a "cracker" they're inferring indirectly that that person is a slave owner. Since most of the time the black person calling the white person a cracker assumes they are racist, you'd really just be complimenting them... Just a thought.
It's never really used, so I haven't grown up hearing it and it doesn't bother me. Actually, most racial slurs don't bother me, because I know the person giving them is simply retarded and should be pitied.
I have more important things to worry about besides being called something like that. It just shows me that the said person calling me that wears racial issues on their sleeve, and isn't worth my time or energy.
My older brother is white and he uses the word cracker to describe our white family all the time(my twin and I are the only black/bi-racial members of our family). He likes to call our mom a gramcracker and he calls my sister and I chocolate crackers...sweatdrop. Personally I wouldn't use that. I've had plenty of white people make black jokes in my presence(my so called friends..."No offense but this is really funny..."wink so, for me I wouldn't call anyone a cracker because whether they tell you or not they might find it offensive and it is kind of a racial slur so....even if my brother uses it to refer to himself and white people I won't use it.