is getting generous and tons of GMail invites are now available. You don't need to be a expert to generate that cool looking GMail signature graphic. Just check out these two Gmail Signature Generator sites:

gizmo967.mgs3.org/Gmail/
playtime.uni.cc/gmail.php

Playtime allows you to download the source code of the gmail signature generator script but I personally like the styles of gizmo967.
email address of amit agarwal

Both these services are very simple to use: Enter you GMail username, click the 'Create' button and save the generated graphic as a .png file. Convert it other formats like .jpg or .gif using free tool like IrfanView. Done ! And putting a graphic instead of the email prevents you from spam as well.

Some more services for GMail and other popular email services.

1. http://www.nhacks.com/email/index.php - Get email graphic signatures for GMail, Hotmail, Yahoo, MSN, AOL, ATT, Bigfoot, RocketMail, QQ, Comcast, Netscape, Blueyonder, SBCGlobal, Earthlink and Lycos

2. http://www.hkwebs.net/catalog/tools/gmail/ - Only for GMail

3. http://createsigs.com/ - Generate a cool looking signature for free to use on GMail, Hotmail, MSN, Yahoo!, AOL, ATT, Bigfoot, QQ