Tcl/Tk, 130129 bytes
time {incr j time {grid [text .t[incr i]_$ji]$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up! 
Tcl/Tk, 130 bytes
time {incr j time {grid [text .t[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
Tcl/Tk, 129 bytes
time {incr j time {grid [text .t[incr i]$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
[Tcl]Tcl/Tk, 130 bytes
time {incr j time {grid [text .t[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
[Tcl], 130 bytes
time {incr j time {grid [text .t[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
Tcl/Tk, 130 bytes
time {incr j time {grid [text .t[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
Tcl[Tcl], 132130 bytes
time {incr j time {grid [button[text .b[incrt[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
Tcl, 132 bytes
time {incr j time {grid [button .b[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!
[Tcl], 130 bytes
time {incr j time {grid [text .t[incr i]_$j -bg [expr ([incr n]+$j)%2?"#000":"#FFF"] -wi 6 -he 3] -row $j -column $i} 8 set i 0} 8 Could not get exactly 50 pixels per square, so I went to a round-up!