Beneficiaries are useful in the case of @likwid, as setting them as beneficiary will liquify the percentage of your reward SP allocated to them into liquid STEEM.

Also, for declining rewards (@null) or supporting proposals (@steem.dao)

Also, SteemPeak supports 10 tags, important for tribes.

Setting a Custom slug, and the only thing holding me from jumping onto Engrave is that I don't have total control over theme customisation (or using CSS stylesheets for example)