Hi I have two suggestions that I think would be quite good to implement.

I'll start with the most simple first:  when creating a puzzle/diagram etc have the "show cordinates" box selected by default.  Why? because I'm sure many (including myself) find it hard to follow analysis without the co-ordinates, and i'm sure many people dont put the co-ordinates on diagrams not because they hate them but because they forget/are lazy/dont know how.

2) When creating diagrams/puzzles/ etc Have a "export as PGN" button. (you already have an import feature running smoothly, so i dont think that this would be too difficualt. That said, i'm not a programmer)

The reason being is that last night I was doing some in depth analysis on a friends game, but when I tried to insert the diagram to a PM something messed up somewhere and the message never got sent and my analysis was totally lost.

An 'Export pgn' button would have allowed me to create a backup of my work. Which, in this particular case would have been useful. 

That second one, where you lost your work is really annoying.  I don't know how long you've got, but if there is no server activity for like 20 minutes, the page times out and "dies".   You need to "SAVE & PREVIEW" often to avoid it, or copy the entire post to your clipboard before submitting it or you lose your post/message permanently.  This is one of the most frustrating things about chess.com.  Having an export might be useful, but I personally wouldn't bother, I tend to find that selecing it all and COPY is good enough, but for major works I would certainly make use of it.

The co-ordinates is a bit of a non-issue though.

Actually for major works I would probably make it a blog post first and use that Save and Preview option and Message a link to it when complete :Þ

I spent about a hour, so server reset might have been a cause.

Usually it not a problem because I'll do the work in fritz 8 and then copy the whole file...this time I didnt do that and I bit me in the arse. 

But, if there is a save function and a you can copy the whole thing (which I didnt realise) perhaps this entire thread is a bit of a non-issue.

oh well, at least I know for next time.

Not really a non-issue imo, the problem should really be fixed.  Making the user lose their work because they've spent an hour composing a really helpful/useful post/message is definitely not desireable and this is the only site I know that does it.