The new PowerShell ISE script editor that ships with PowerShell v3 has a much improved IntelliSense (code completion) that you can even fine-tune from PowerShell. Here are some interesting options you may want to try:
$psISE.Options.IntellisenseTimeoutInSeconds $psISE.Options.ShowIntellisenseInConsolePane $psISE.Options.ShowIntellisenseInScriptPane $psISE.Options.UseEnterToSelectInConsolePaneIntellisense $psISE.Options.UseEnterToSelectInScriptPaneIntellisense