I read recently that GMail lets you set the From: address in emails that you send from the Web interface, so I went looking for the setting as it would let me use GMail for webmail for all my email accounts and hide the @gmail.com address. According to the site I read it from, you need to click the Settings link and then Accounts. This didn't appear for me, until I tried switching to English (US) instead of English (UK). Now I can add several From: addresses and switch between them, which saves me running my own webmail software. Putting it here just in case it's useful to anyone else.