Suggestions for newthm

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

Package thmlist: A LaTeX package for adding theorem environments quickly
Package create-theorem: Initializing and configuring theorem-like environments, with multilingual support
Package phfthm: Goodies for theorems and proofs
Package inkpaper: A mathematical paper template
Package rmthm: Use a roman font for theorem statements
Package linkedthm: Hyperlinked theorem–proof environments for LaTeX
Package nccthm: Another theorem environment
Package statementsp: Theorem and proposition boxes with preview and recall functions
Package reptheorem: Repetition of theorem environments
Package autobreak: Simple line breaking of long formulae
Package thmtools: Extensions to theorem environments
Package thrmappendix: Theorems, lemmas, etc., in appendix
Package newproof: Make commands to define proofs
Package csthm: Customized theorem environments for computer science documents
Package coolthms: Reference items in a theorem environment
Package thmbox: Decorate theorem statements
Package theorem: Manipulate theorem environments
Package shadethm: Theorem environments that are shaded
Package ntheorem: Enhanced theorem environment
Package amsthm: Typesetting theorems (AMS style)
Package propositions: Typeset and cross-reference named and numbered propositions
Package spalign: Typeset matrices and arrays with spaces and semicolons as delimiters
Package keytheorems: An l3keys interface to amsthm
Package proofgraph: Dependency graphs of the results of a mathematical article
Package coloredtheorem: A colourful boxed theorem environment
Package theoremref: References with automatic theorem names
Package linenoamsmath: Use the lineno package together with amsmath
Package penrose: A TikZ library for producing Penrose tilings
Package voss-mathmode: A comprehensive review of mathematics in (La)TeX
Package pzccal: Zapf Chancery as calligraphic math alphabet
Package mathptmx: Use Times as default text font, and provide maths support