Here’s a quick tip for increasing the size of the thumbnails in a SharePoint 2010 Slide Library.
When viewing AllItems.aspx, do the following:
1. Go to the Ribbon and click Library under Library Tools.
2. Click Modify View.
3. Deselect the Thumbnail column (position 2).
4. Scroll down and select the OTHER column cleverly named Thumbnail and set it to Position 2.
5. Click OK.
This will display your thumbnails in a resolution of 256 x 192 pixels instead of the default resolution of 83 x 63 pixels. Admittedly, this is not the best solution available, but it would be hard to beat the price.
spfarmboy 
This is what I like, quick easy solutions to problems for people who should who should not be digging too deeply into the “guts” of SharePoint. Thanks very much spfarmboy
Hi! do you have any idea how to set up a view of the slide library so that the slides are presented with thumbnails and a checkbox like the tiled picture view? it would be so much better to select view the slides this way.
Unfortunately, no. The Default view does have Selection Checkboxes on the left, but I see no way to present this as a tiled view OOTB. You might be able to do something in SP Designer, but I haven’t investigated this.
JFYI – a solution for thumbnails preview in SharePoint 2010/2013: http://www.harepoint.com/Products/HarePointThumbnails/Default.aspx
Note it allows to generate preview in SharePoint libraries both for images and files (.doc, .xls, .pdf, etc).