VSCommands - not an alternative per se, but rather a complementary tool with plenty of unique features not available in ReSharper/CodeRush/JustCode
From the website:
IDE Enhancements
* Custom Formatting
o Build Output
o Debug Output
o Search Output
* Solution Properties
o Manage Reference Paths
o Manage Project Properties
* Apply Fix
o File being used by another process
o StyleCop warnings
o Importing .pfx key file was cancelled
* Search Online
* Cancel Build When First Project Fails
* Advanced Zooming
Solution Explorer Enhancements
* Prevent Accidental Drag & Drop
* Prevent Accidental Linked Item Delete
* Group / Ungroup Items
* Show Assembly Details
* Build Startup Projects
* Open Command Prompt
* Open PowerShell
* Locate Source File
* Open File Location
* Show / Hide All Files
* Edit Project / Solution File
* Copy / Paste As Link
* Copy / Paste Reference
* Open In Expression Blend
* Collapse All
* Clean All Build Configurations
Debugging Assistance
* Attach To Local IIS
* Debug As Administrator
* Debug As Normal user
* Debug As Different user
Code Assistance
* Create Code Contract