Tape or grips for bar ends? I've just added a pair of bar ends to my handlebar. I feels surprisingly good, except that they are too thin, compared to my grips.

Are there any options to make them more comfortable? Maybe I can put a bar tape on them? If so, should I look for some specific type of this tape?

This is a picture of them if it helps.
Adding bar tape to the bar-ends is certainly possible. What kind of tape you want to use is determined by your preference. There are both thin and thick types available. If the bars still feel to thin after applying a layer of tape you can try double-wrapping them.

Drop bars are wrapped from the ends towards the stem, with the starting end of the tape tape tucked into the end of the bar, secured with the end-plug. You may have trouble getting thick tape into the end of the bar-end as they are of somewhat smaller diameter than drop bars. The other end is simply secured with tape.

Direction of wrap is important, force from the hands tends to be downwards on the outside of the drops section of drop bars, so you will want the direction of wrap to be downwards on the outside also.

This Park Tool video may help you.