Various PowerShell scripts that I have written/modified. Most are geared towards SharePoint.
##delete-userprofiles deletes user profiles with a certain prefix, i.e. domain
##enable-developerdashboardforadmins turns on developer dashboard, but only for full control
##get-spserverbyrole returns servers in a farm based on type (web application, central admin, database) i use this when checking server settings / artifacts based on role (i.e. deploy pdf icon to servers hosting web applications)
##impersonate-spsite gets a spsite object using the token of a specified user, "impersonating" the object
##reset-sptimerservicecache clears the timer service cache on the local server by stopping sptimerv4, clearing the xml files that represent objects in the config db, setting the ini file to 1, and restarting the service
##set-sppeoplepicker sets people picker properties to limit lookup
##verify-loopbackcheck verifies that loopback has been disabled through the registry
##verify-spfeaturescope checks for features that do not have a scope specified. i have seen this occur numerous times with custom features, which can cause orphaned items in the config db and/or filesystem
##verify-spoutputcachelimit this is an enhancement on a todd carter blog post (see script comments for url) that checks the number of uniquely secured items in a site collection to verify if output cache will function. it can output the sql statement that needs to be run, or it can attempt to execute it itself
##verify-spsearchqueryservice verifies that the search query and site settings service is running and running only on query components
##verify-spuilsync wraps stsadm -o sync -listolddatabases 1 to see how many content databases need to be synced
##verify-spwebapplicationportalaccounts checks each web application (except ca) to verify that the portal superuser and superreader accounts are set
##verify-spwebparts checks a publishing page for potential web part performance issues (custom, closed, audience, cqwp, cqwp with/audience filtering, etc.) this will not work in foundation