I just came across this nice template for BibDesk that will display your Skim notes in a preview pane. My new BibDesk layout has the notes preview in the right-hand pane and the files preview in the lower pane. Also, note that in the files display, there is a hidden zoom control in the top center.
Get the “previewTemplate” here at Jim Harrison’s templates page . To install it, put previewTemplate.rtf in ~/Library/Application\ Support/BibDesk/Templates/ and then go into the BibDesk Templates preference pane, make sure nothing is selected, and hit the + button. Click on the new name twice slowly and give it a name like “previewTemplate”, and double-click on the file to choose the previewTemplate.rtf file you just put into your Library folder. Finally, select the previewTemplate from the template popup under the pane you want to put the preview template in.