Here is my unofficial list of all the Virtual machines available for download.  you can check the official VHD TestDrive website, but there is a larger list below:

  1. Forefront Codename Stirling VHD - 15.9 Gb
  2. Internet Explorer 8 Compatibility VPC Image - 500 Meg
  3. WS08_RTM_x86_EnterpriseVHD.zip (single file)
  4. WS08_ServerCorex86_EnterpriseVHD.zip (single file)
  5. WS08_RTM_x64_EnterpriseFULL.zip
  6. ServerCorex64_Enterprise.zip
  7. Windows SharePoint Services 3.0 SP1 Developer Evaluation VPC Image - 3.4Gb
  8. Visual Studio® Team System 2008 TFS VPC Image (Trial) - 4.9Gb
  9. Visual Studio® Team System 2008 TFS and Team Suite VPC Image (Trial) - 2.9 Gb
  10. Identity Lifecyle Manager 2007 VHD - 3.3Gb
  11. Internet Explorer Application Compatibility VPC Image - 950 Meg
  12. Microsoft System Center Essentials 2007 VHD - 2.6Gb passport required
  13. Microsoft Exchange Server 2007 SP1 VHD - 32-bit version - 1.8 Gb
  14. Microsoft SQL Server 2008 Community Technology Preview (November 2007) VHD - 2.2 Gb
  15. Search Server 2008 Express VHD - 2.9 Gb
  16. Visual Studio 2008 Beta 2 Team Foundation Server (VPC) - 5.8 Gb
  17. Visual Studio Team System 2008 Beta 2 Team Suite (VPC) - 4.9 Gb
  18. Microsoft System Center Configuration Manager 2007 VHD, 7.5 Gb
  19. System Center Virtual Machine Manager 2007 VHD, 3.0Gb - passport required
  20. SQL 2008 CTP4, 2.2Gb
  21. BizTalk 2006 7.3 Gb.
  22. Exchange Server 2007 SP1 Beta 2 VHD - 32-bit, 1.6Gb
  23. Exchange Server 2007 TD VHD 1.4 Gb
  24. Forefront and System Center Demonstration Toolkit, 1.7Gb - passport required
  25. Internet Explorer 6 Application Compatibility VPC Image, 495Mb
  26. Internet Explorer 7 Application Compatibility VPC Image, 491 Mb
  27. ISA Server 2006 TD VHD 1.5 Gb
  28. Microsoft Dynamics CRM 3.0 VPC, 2.4Gb
  29. Microsoft Visual Studio 2005 Team Suite VHD, (rel 1.0) 3.9 Gb
  30. Microsoft Visual Studio 2005 Team Suite VHD, (rel 1.1) 2.7 Gb
  31. Microsoft Windows Vista VHD, 1.6 Gb - WGA required (rel 1.0)
  32. Microsoft Windows Vista VHD, 1.6 Gb - WGA required (rel 1.1)
  33. Office 2007 Professional VHD, 2.5 Gb - passport required
  34. Office SharePoint Server 2007 VHD, 3.7 Gb - passport required
  35. SCVMM Beta 2 VHD, 1.8 Gb - passport required
  36. SQL Server 2005 TD VHD 2.4Gb
  37. SQL Server 2005/Exchange 2007, 3.3 Gb - passport required
  38. System Centre Essentials VHD. 3.2 Gb
  39. Visual Studio 2005 Team System Basics Training, 5.2Gb
  40. Visual Studio Code Name Orcas Base Image, 1.1Gb
  41. Visual Studio Code Orcas Beta 1 Team Suite (VPC), 5.4 Gb
  42. Visual Studio Orcas Beta 1 Team Foundation Server (VPC), 6.0 Gb
  43. Visual Studio Team System 2008 Beta 2 Team Suite (VPC), 4.6 Gb
  44. Windows 2008 Beta 3, 2.8 Gb
  45. Windows Server 2003 R2 TD VHD 1.4 Gb

Below is a quick list of tools to get you started, tools with a * require registration:

And here are other VHDs:

  1. Citrix Presentation Server Platinum Edition
  2. SUSE Linux Enterprise
  3. ToutVirtual VirtualIQ Professional