I got a gmail account a little while back and like it enough that I thought I'd pimp it a bit (it's the email in my profile). The web interface is fast and simple and has a bunch of features.
For instance, you click on a contact and below the contact info you get a list of all the email you've received from that contact. I'm also using the contacts list as my main address book -- it has the advantage that I can list all the various email addresses some of my friends collect, then collect their emails together.
There's a nice little labelling system where you can label emails in multiple ways and then use those labels to collate stuff. You can also use Google's regular search engine on the material.
The other big thing is that you don't delete emails, you archive them. Google adds a couple megabytes of storage per day to your account so, in theory, you'll just never run out of space and never need to dump an email. They're touting it as inifinite storage since Google plans to exist well past the death of the universe and become some kind of cyber-deity. In turn, I plan to upload my consciousness to Google sometime around 2048 and thereby unify with Google-nature.