The ornamental design for a keyboardholder, as shown and described.
FIG. 1 is a top, side perspective view of a keyboard holder;
FIG. 2 is a bottom, opposite side perspective view;
FIG. 3 is a top plan view on an enlarged scale; and,
FIG. 4 is a sectional view taken on line 4--4 of FIG. 1 on an enlarged
scale, the broken line drawing of a desk and an operator's hand being
shown for illustrative purposes only and forming no part of the claimed
design.