In summary, if you absolutely need to get your data to or from everyone in the world, then really the only way to go is through the web.

If your application is internal or available only to a select few outside then you may want to look in to other technologies that can potentially save you time and money implementing and deploying the application.

Citrix is considered the standard for publishing desktop applications in large companies. Citrix has been around for quite a while and their product is well established.

The newer versions of MS Terminal Server are functionally almost on par with Citrix but it lacks the seamlessness of Citrix and therefore can be somewhat more difficult for users to use.

X11 and VNC are not currently commonly used for publishing applications, but these have the advantage of being Free technologies and there is great potential for both.

Character Cell terminals or terminal emulators are generally looked down upon as being "obsolete" but they still have perfectly legitimate uses. Most hardware terminals have disappeared in favor of desktop PCs with a terminal emulator except where PCs are not practical.
 

	Citrix	TS	X11	VNC	Char Terminal	Client / Server	Web
Supports seamlessly drawn windows.	Y	N	Y	N	N/A	N/A	N/A
Always renders UI precisely as intended.	Y	Y	N	Y	N	Y	N
Widgets and controls can have a native appearance.	N	N	N	N	N/A	Y	Y
Brings application audio to the local machine.	Y	Y	N	N	N (unless you count bleeps)	Y	N (needs plug-in)
Brings remote print jobs to local machine.	Y	Y	N	N	Y	N/A	N/A
Print job is always rendered precisely as intended.	Y	Y	N/A	N/A	Y	Y	N
Fonts only need to be loaded on the server.	Y	Y	N	Y	Y (for printing)	N	N
Can resume session	Y	Y	N	Y	N (depends on server)	N/A	N (depends on server)
Uses constant connection to application server	Y	Y	Y	Y	Y	N/A	N
application CPU processing done on server.	Y	Y	Y	Y	Y	N	N
minimal acceptable bandwidth to application server	28.8k	28.8k	10mb	56k	2400 baud	N/A	28.8k
Client Access Licenses must be purchased	Y	Y	N	N	N	N	N
Client application software cost	included with CAL	included with CAL	Free or $$$	Free	Free or $$$	N/A	Free or $$$
Server software cost	$$$	$$$	Free or $$$	Free	Free or $$$	N/A	Free or $$$
Can handle number of users per server (depends heavily on hardware and application)	hundreds	hundreds	hundreds	hundreds	thousands	N/A	thousands
Cross platform client software	Y	Y	Y	Y	Y	Depends on app	Y (Unless app is IE only, in which case NO)
Cross platform server software	Y	N	Y	Y (Multi -user for Unix / Linux only)	Y	N/A	Y
Buzzword compliant	N	N	N	N	N	N	Y