Suggestions for sublabel
The following packages have something in common with the package sublabel. The packages are ordered in decreasing similarity.
- smartref: Extend LaTeX's \ref capability
 - totalcount: Commands for typesetting total values of counters
 - counterz: Additional tools for counters
 - autonum: Automatic equation references
 - crossreference: Crossreferences within documents
 - deleq: Flexible numbering of equations
 - fancyref: A LaTeX package for fancy cross-referencing
 - issuulinks: Produce external links instead of internal ones
 - modref: Customisation of cross-references in LaTeX
 - numberedblock: Print a block of code, with unique index number
 - philex: Cross references for named and numbered environments
 - saferef: Safer references through strong typing of references
 - typedref: Eliminate errors by enforcing the types of labels
 - totpages: Count pages in a document, and report last page number
 - termlist: Label any kind of term with a continuous counter
 - fancylabel: Complex labelling with LaTeX
 - refenums: Define named items and provide back-references with that name
 - chemsec: Automated creation of numeric entity labels
 - inlinelabel: Assign equation numbers to inline equations
 - crossreftools: Expandable extraction of cleveref data
 - cleveref: Intelligent cross-referencing
 - fncylab: Alter the format of \label references
 - refcount: Counter operations with label references
 - hereapplies: A LaTeX package for referencing groups of pages that share something in common
 - wtref: Extend LaTeX’s cross-reference system
 - refstyle: Advanced formatting of cross references
 - crefthe: Cross referencing with proper definite articles and declensions
 - cleveref-usedon: Adds forward-referencing functionality to the cleveref package
 - undolabl: Override existing labels
 - bibleref: Format bible citations
 - zref: A new reference scheme for LaTeX