One of the trickiest parts of throwing an event is sending out invitations and tracking RSVPs. Here's the skinny on three online services that can handle the tedious tasks for you.

Amiando

With Amiando's formatted templates, you can create event registration websites and e-mail invitations and track responses online. To RSVP, people click on a registration link in the e-vite (you can also promote the events online), fill out a form, and make a payment via PayPal, credit card, or invoice. cost: No charge for free events, then $1 per ticket, plus a 6 percent surcharge.

Eventbrite

Eventbrite also lets you create event websites and e-mail invitations, collect payments, and track responses. Unlike Amiando, it also tracks how many people clicked on a registration page through, say, Facebook or Twitter, as well as e-mail. cost: No charge for free events, then 99 cents per ticket, plus a 2.5 percent surcharge.

Constant Contact

Constant Contact's Event Marketing tool lets you track real-time information such as venue capacity as well as RSVPs and payments. You also can add custom fields to response forms to gather more detailed information. cost: After a free 60-day trial, there is a flat monthly fee starting at $15 for five events with up to 2,000 attendees.

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