C, 256 chars
Approximates pi using the algorithm in @Sukminder's code (shamelessly borrowing and refactoring their code a bit). Outputs a binary PBM image, which could then e.g. be converted with ImageMagick.
b,c=70,d,e,f[71],g;v[71],j,k;L[]={1072684944,792425072,492082832,256581624,0}; main(){puts("P4\n8 100");for(;b<c;)f[b++]=2;for(;d=0,g=c*2;c-=1,e=d%10){ for(b=c;d+=f[b]*10,f[b]=d%--g,d/=g--,--b;d*=b);v[j++]=e+d/10;} for(;k<100;k++)putchar(L[k%5]>>3*v[k/5]&7);} Here's what the output looks like with my Braille-based PPM renderer:
Has the same quirk as @Sukminder's answer in that it lacks a decimal separator. In addition, the output of mine is vertical, and whether it's human-readable is arguable...