Clocks and Time
Scripts that display current time/ date.

Mailing Lists
Keep in touch with your visitors by adding a mailinglist to your site.

Password protecting
Protect your files/ directories from intruders.

Link redirection
Redirect your users to an appropriate page.

Shopping carts
Shopping cart scripts.

Surveys and polls
Live poll/survey.

Forms
Form processing scripts.

Miscellanous
Anything that does not fall into one of the categories

Games
Various Games.

File Uploading
File uploading scripts.

Auctions
Add auction scripts to your web site.

Message forums - BBS
Interactivity and something to keep visitors involved.

Virtual Post Cards
Have your visitors send virtual post cards to their friend and family.

Images
Various scripts for manipulation and use of images.

Search
Search scripts / local and internet.

Text
Various text manipulation scripts.

Guestbooks
Nice way to leave a remark.

Website Promotion
Promote your web site with these scripts.

Classified Ads
Place your classified advertising script on your page and draw more people to your site.

Calendars
Event calendar for your and others.