I have been using all four, and they seem to be working out. None of 
them are TOO too slow.  But I haven't fully investigated or tracked for 
'non-consistent performance', not sure what you mean there, just that 
sometimes it's slow?   All of those seem to work fairly well for me.

There is another source of free _movie_ cover images, but I forget what 
it is and haven't investigated it yet. Also there are several sources 
for free musical album cover images, which likewise I haven't 
investigated yet but would like to.

Jonathan

Edward M. Corrado wrote:
> Hello all,
>
> We are reevaluating our source of cover images. At this point I have 
> identified four possible sources of free images:
>
> 1. Amazon
> 2. Google Books
> 3. LibraryThing
> 4. OpenLibrary
>
> I know that their is some question if the Amazon and Google books images 
> will allow this (although I've also yet to hear Amazon or Google telling 
> libraries that use their Web services for this to cease and desist). 
> However, besides that issue, has anyone noticed any technical problems 
> with any of these four? I'm especially concerned about slow and/or 
> non-consistent performance.
>
> Edward
>
>