Ipod Classic
7th Generation

Ipod Shuffle
4th Generation
Ipod Nano 5th Generation
Ipod Touch 3rd Generation
160 GB 4 GB 8 GB 16 GB 8 GB 32 GB 64 GB
30,000 Songs 1,000 2,000 4,000 1,750 3,500 7,000
Classic
Touch
iPad

The Apple iPod Touch was a revolutionary device. It is based on the Apple iPhone. With this product, Apple expanded from just providing a basic MP3 player to providing a full fledged computer for the same price. With Wifi, it can provide several of the same functions as the iPhone. It has access to all the major apps. The latest generation includes a front and rear facing camera along with a built in microphone. With wifi applications like Facetime, Skype, and Fring, the latest iPod touch can act like a wifi phone. Beyond video and music, the iPod touch supports over 300,000 apps.

Here is a small directory of good applications by category.

Finance:
CNBC, Bloomberg, AOL Finance, Yahoo Finance

Communication:
Skype, Fring, AIM
With Skype, it is possible to use the Touch as a phone after buying a telephone number and getting an unlimited call plan. 

Video:
Netflix, Youtube, Vevo

Reviews:
Yelp

Search:
Google, Bing

Maps:
Google, Mapquest