I hate only having the chance to hold 250 messages in my PM box and I also dont like how short our siggys have to be. SO what I propose is this.
Every level that you gain on the site (clraik, Official Clriak, Top Clraik etc) you gain a larger PM box and a bigger siggy size. This way it promotes more activity on the site and more contributions and it gives benefits to those who use the site more often/need more pm space...
I find myself clearing out my pm box since its completely full like every 2 days...Just a suggestion though might help out more activity/contributions (to get the rep) to the site!