Microsoft Office Web Apps and SharePoint 2010: Error Time-Suck

In one of my SharePoint 2010 sites, I was getting this nasty error that was preventing me from opening a Microsoft Word file and editing it within the browser:

"Word Web App cannot open this document for viewing because of an unexpected error."  Also, when I tried to open an Excel document, I got a "Cannot open the workbook" error.  Perplexed, I scoured the web and phoned a friend or two.  In the end, these 2 things got my issue resolved:

1. Give the SharePoint Service account user dbcreator privileges in the SQL Server Security for your installation.
2. Execute the following PowerShell commands (if you didn't when you set up OWA in the first place):
   
   $webApp = Get-SPWebApplication http://sharepointsite/url/tosite
   
   $webApp.GrantAccessToProcessIdentity("domain\user_owa_runs_under")

I hope this saves someone some trouble because this cost me about 3 hours of frustration.

Now on to the fun stuff!