Suggestions for theorem

The following packages have something in common with the package theorem. The packages are ordered in decreasing similarity.

Package amsthm: Typesetting theorems (AMS style)
Package ftnright: Footnotes in two column documents in one column only
Package layout: View the layout of a document
Package enumerate: Lists with redefinable labels
Package bm: Access bold symbols in maths mode
Package autobreak: Simple line breaking of long formulae
Package thmtools: Extensions to theorem environments
Package multicol: Intermix single and multiple columns
Package tabularx: Tabulars with adjustable-width columns
Package newproof: Make commands to define proofs
Package thmbox: Decorate theorem statements
Package shadethm: Theorem environments that are shaded
Package ntheorem: Enhanced theorem environment
Package amscls: AMS document classes for LaTeX
Package array: Extending the array and tabular environments
Package afterpage: Execute command after the next page break
Package calc: Simple arithmetic in LaTeX commands
Package dcolumn: Align on the decimal point of numbers in tabular columns
Package delarray: Delimiters for arrays
Package fontsmpl: Print a sample of a font
Package hhline: Better horizontal lines in tabulars and arrays
Package indentfirst: Indent first paragraph after section header
Package longtable: Allow tables to flow over page boundaries
Package rawfonts: Low level font compatibility mode for LaTeX
Package somedefs: Save loading all of another package
Package shellesc: Unified shell escape interface for LaTeX
Package trace: Make sensible use of TeX tracing in LaTeX
Package varioref: Intelligent page references
Package verbatim: Reimplementation of and extensions to LaTeX verbatim
Package xspace: Define commands that appear not to eat spaces
Package theoremref: References with automatic theorem names