spyware

Spy-ware is Internet jargon for Advertising Supported software (Ad-ware). It is a way for shareware authors to make money from a product, other than by selling it to the users. There are several large media companies that offer them to place banner ads in their products in exchange for a portion of the revenue from banner sales. This way, you don't have to pay for the software and the developers are still getting paid. If you find the banners annoying, there is usually an option to remove them, by paying the regular licensing fee.Known spywares
There are thousands out there, new ones are added to the list everyday. But here are a few:
Alexa, Aureate/Radiate, BargainBuddy, ClickTillUWin, Conducent Timesink, Cydoor, Comet Cursor, eZula/KaZaa Toptext, Flashpoint/Flashtrack, Flyswat, Gator, GoHip, Hotbar, ISTbar, Lions Pride Enterprises/Blazing Logic/Trek Blue, Lop (C2Media), Mattel Brodcast, Morpheus, NewDotNet, Realplayer, Songspy, Xupiter, Web3000, WebHancer, Windows Messenger Service.How to check if a program has spyware?
The is this Little site that keeps a database of programs that are known to install spyware.

Check Here: http://www.spywareguide.com/product_search.php

If you would like to block pop-ups (IE Pop-ups).
There tons of different types out there, but these are the 2 best, i think.

Try: Google Toolbar (http://toolbar.google.com/) This program is Free
Try: AdMuncher (http://www.admuncher.com) This program is Shareware

If you want to remove the "spyware" try these.
Try: Lavasoft Ad-Aware (http://www.lavasoftusa.com/) This program is Free
Info: Ad-aware is a multi spyware removal utility, that scans your memory, registry and hard drives for known spyware components and lets you remove them. The included backup-manager lets you reinstall a backup, offers and multi language support.

Try: Spybot-S&D (http://www.safer-networking.org/) This program is Free
Info: Detects and removes spyware of different kinds (dialers, loggers, trojans, user tracks) from your computer. Blocks ActiveX downloads, tracking cookies and other threats. Over 10,000 detection files and entries. Provides detailed information about found problems.

Try: BPS Spyware and Adware Remover (http://www.bulletproofsoft.com/spyware-remover.html) This program is Shareware
Info: Adware, spyware, trackware and big brotherware removal utility with multi-language support. It scans your memory, registry and drives for known spyware and lets you remove them. Displays a list and lets you select the items you'd like to remove.

Try: Spy Sweeper v2.2 (http://www.webroot.com/wb/products/spysweeper/index.php) This program is Shareware
Info: Detects and removes spyware of different kinds (dialers, loggers, trojans, user tracks) from your computer.
The best scanner out there, and updated all the time.

Try: HijackThis 1.97.7 (http://www.spywareinfo.com/~merijn/downloads.html) This program is Freeware
Info: HijackThis is a tool, that lists all installed browser add-on, buttons, startup items and allows you to inspect them, and optionally remove selected items.