With the AccuDial app from AccuConference you can join conference calls without having to remember any of your numbers or codes. The app saves all of your dial-in phone numbers and codes, so all you have to do is fire it up, select the conference by name and press "join." If any of your conference codes change, you can easily edit them from the settings page.
Another feature lets you email invitations to your contacts. Select which contacts you'd like to invite to the conference, send the invite, and all of the conference information will be included in the email.
AccuDial stores as many conferences as you need. It's available for free in Apple's App Store or the Android Market.