There are a few lite implementations available on the web for GMail but this has to be the most attractive (at least when viewed from a desktop browser. Pocket GMail offers a version of GMail formatted for PDA-sized screens and although Pocket GMail is setup to graphically represent a Pocket PC device, it can be viewed from any PDA browser of the correct size. Best of all, the source is available so you can setup the system on your own server and feel comfortable about entering your account ID and password! Pocket GMail is based on libGMail.

Source: Pocket GMail