The JewishGen Yizkor Book Master Name Index

Surname searches every name field: not just the deceased, but spouses, parents, and relatives named in a record's comments. Maiden names are included where known.

Phonetically Like (the default): Groups names that sound alike across languages. Hebrew engravings are transliterated, so spellings vary - this or Sounds Like works best.
Schwartz also finds Shvarts, Cvartz.

Given Name: Where only a Hebrew name was recorded, it may be indexed as the given name - so search given names as well as surnames.

Town: Returns cemeteries located in that town, landsmanshaft sections for it elsewhere, and records that mention it in a place or comment field. Town names only - no country, state, province, or gubernia.

Comma = OR, Space = AND: A comma finds either name; a space requires both.
Schwartz, Weiss vs. Schwartz Weiss.

Narrow by place last: Search by name first; add a region only if you get too many hits. Borders and town names shifted constantly, so an early filter can hide the record you want.