Client, Server and UDP on one Arduino

I'm using an arduino uno - Binary sketch size: 15470 bytes (of a 32256 byte maximum)

That is the amount of FLASH (also known as program memory) THe Arduino has separated program and data memory.


If I understand your suggestion right the "program" should run like this:

Webserver, NTP, Pachube
Ethernet Init -> UDP init -> NTP get -> UDP stop -> Webserver start -> look for webserver data -> Webserver stop -> Pachube Client start-> Pachube update -> Pachub Client Stop -> End
Own function:
NTP - including UDP init, NTP get, UDP stop
Webserver - including Webserver start, look for webserver data, Webserver stop
Pachube - including Pachube client init, Pachube update, Pachube Client stop

Yes you got the idea

in pseudocode
loop()
{
HowLongCanTheWebRun = max (24 hours, howLongUNtil NTP, howLongUNtilPachube);

runTheWeb for HowLongCanTheWebRun;

if (time to runNTP) doNTP();

if (time to Pachube) doPachube()
}

Do you have a link to the Alarm library used?