I've been using Gixen for almost 4 years. I'm writing this review because of a request on the login page to share our experiences with the users of this site. Thats a very easy request to fulfill for an author whom has done a great deal and asked very little in return.
The service is free with an option to upgrade to a mirror service with a few more perks (no ads, slight customizations, etc.) To be honest most people don't need the mirror service. I know for a fact though from the forums that a great deal of people get it solely to show their support for a great site that has saved them considerably more in time, frustration, and just good old cash. Besides it's so cheap that you feel guilty for not doing it (a first for me). Plus now there is a desktop app you can get with your contribution.
Put in a few snipes, your login info will be safe and is worth doing to get over that initial concern. If it still bugs ya, look in gixen's FAQs for a free computer based option that will place the bids from your system. The sites author even takes the time to outline and link all your other options.
Honestly, I don't bid without it, my sleep and time are worth more to me than following an auction for a material object. put in the bid, get the item, go on with your life.
P.S. Grouping snipes are a god send and save me huge sums of money.