If your clients are seeking entertainment, by all means entertain them ! However if your clients are other business people seeking a service or product, chances are the easier it is for them to find exactly what they want without a lot of hassle will result in a satisfied visitor. Remember, business web surfers are online for a purpose and don't often have time to waste. They will appreciate a simple, easy to navigate site that give them what they need as quickly as possible.
Text: Information is the core of any web site. Without text information you don't have much need for a web site. Text is also the meat that search engines digest. Make it clear, easy for the average visitor to understand. Make sure to use important key words in a manner that makes sense. Distribute your text content on several pages designed to convey single ideas. These should include a page title and description in the first paragraph so visitors and search engines understand what you are saying. Be prepared to spend some time composing informative text information for your web master. Most web design companies are not going to be experts in YOUR business and won't know what to say.
Images: Images are a natural part of most web sites. In the most basic design, you should display at least your company logo. Don't go overboard on images that don't promote your key products or services. If you have a portfolio of your work to display this is great. Consider a gallery or slideshow presentation if you have a lot of them and wish to be able to manage them yourself. Always be careful about copyright issues and use only images you know you have permission to publish.
Color: There are studies that show the effects of various colors on visitors. For instance red is associated with excitement and impulse purchases. Darker colors tend to instill more of a confidence in visitors.
Sound: Music is useful if you sell music ! For most visitors adding music is a nuisance. Your choice of tunes will not be welcomed by all. Avoid Music or sounds except where part of a specific presentation or video. If you do use sounds or music make sure you have legal right to do so before publishing. You could find yourself on the wrong end of a law suit.
Motion: Animation that does not serve the purposes of your site should be avoided. A little motion goes a long way but such simple forms such as roll-over effects can be a tasteful means to add a little dynamics to your site without distracting people from their surfing.
Gadgets: When done tastefully a useful widget or gadget is ok. If most of your customers will be local, placing the current weather on your site is ok. If your clients are all over the place, they have no interest in your weather. If your business is related to banking or investments, some form of live stock ticker may be appropriate. A mortgage or real estate site can do with a few mortgage or loan calculators. If you want a gadget of some kind keep in in the context of your site's purpose.