Cydia only has a certain amount of applications when you first install it. The way that you add more applications is by adding more repositories, which are simply web addresses that you send Cydia to gather application information in order to install things. These Cydia repositories are numerous, and can be quite overwhelming if you don't know what you're looking for. It is for this reason that I am giving you a guide to Cydia repositories. To begin, I will tell you how to add a Cydia repository. First, open up Cydia.
Next, click on the middle button that says 'Sources.'
After that, select 'Edit' in the top right corner, then 'Add' in the top left.
Choose a Source URL from the list below, enter it in to the box, and select 'Add Source.'
Then, you can select the source in order to see what applications that repository has to offer. In addition to that, the apps from the repository will be added to the main list of apps in Cydia.
Here's a large list of repositories, some of which you may already have. I'll keep updating it as I discover more and more repositories. Feel free to recommend some to me, as well.:
BigBoss & Planet-iPhones Applications, Utilities, and Themes http://apt.bigboss.us.com/repofiles/cydia/
iSpazio Mostly Themes, with some utilities http://ispaziorepository.com/
miPhone Themes and Tweaks http://cydia.miphone.ca/repo/
ModMyi.com Tons of everything: games, utilities, themes, etc. http://apt.modmyi.com/
Darvens Repository Themes, Tweaks, Apps, and Wallpapers http://apt.guardiansofchaos.com
Xsellize Backgrounds, Games, Apps, and Themes http://xsellize.com/cydia/
Hackulous Hacks http://cydia.hackulo.us/
Hack&Dev Utilities and Tweaks http://iphone.hackndev.org/apt/
iPhoneStuff Customization Apps and Utilities http://iphonestuff.ru/
Ranbee Utilities and Customization http://ranbee.com/repo/ Another way that you can add Cydia repositories is through packages. Select 'Sections' at the bottom of Cydia.
Next, click on 'Repositories.'
From the list, you can install any repositories that take your fancy just as you would install any other application.