How would you reduce Gmail storage size?

Ask if deletion is an option. What does reduce Gmail storage size mean? Reduce per user quota? Free up disk space? Less data overhead in the DB? Clarify what exactly “reduce Gmail storage size” is without sounding like an idiot. 

For e.g., the question might be rephrased as 

"You have a 15GB GMail account and Google has decided to make all GMail accounts 10GB, what do you do now". Yea, yea that's dumb and Google won't pull that stunt but that's not the point. The point is to show Google that you aren't a pencil pusher.

Is there an option to provide offline downloads of e-mail before deletion? As in a very easy way (one click download – think of Facebook data download) instead of forcing users to use POP3/IMAP clients.

Is there an option to sort emails by size and/or date? [There is but this isn’t user friendly].

Is there an option to mass-archive e-mails? Text lends itself to incredible compression(needs to be lossless – RLE). However attachments might still be a problem (images may be lossy?)

Provide option to save e-mails and/or DOC attachments to something like Google Docs (unlimited space!). Offer conversion of non-support documents to documents that Google Docs supports.

Look into databases/backend with least data overhead?