Imp.guru has now closed down and Sparkfun have changed some protocol or other and it also does not now work, so you will have to find other sites to post the data to . The rest is still very usable just the software lines need to be changed to accommodate the new site.
Sparkfun Electronics have made available a site data.sparkfun.com
that accepts your data regularly and stores it for retrieval by you at any time . The site is protected by a password key setup where you are given a private and a public key. Your data is public but only you can change it. Here is my data https://data.sparkfun.com/streams/RMzp9ANyqzfjw4drzNnZ In graph form http://imp.guru/f30 It has been belting down rain for a few weeks now and my setup is now powered by the modem directly so is only on when my modem is on and thats only when I am using the internet.
Arduino board (or ATMega328p chip or any Arduino type chip really but you have to attach the shield and sensors . Arduino Pro or Pro mini boards are on the internet for $3 from china )
Ethernet shield (Heaps of these . I got one for $12 in OZ) Ebay search link is
Power supply (Wall wart or direct to modem)
Cat5 cable(your length)
Software (see below Arduino code in zip file attached)
SFE_BMP180 pressure and temp from sparkfun https://www.sparkfun.com/products/11824?_ga=1.134489585.1483023871.1423973461
my sensor RHT03 from sparkfun https://www.sparkfun.com/products/10167
Place the Ethernet shield on the arduino board and connect the sensors .connect the ethernet shield to the modem and power up the Arduino.
Using it exactly as I have it set up results in data being recorded every half hour .
There is also a site http://imp.guru/ " Imp Guru" that takes your data ,which anybody has access to , and pumps it into a continuous graph form . They simply put mine on and told me about it so how they choose I don't know but you can email them on their home page contact email page.EDIT Now gone so follow their new site .
Below is the code to put on the Arduino. Download the zip and extract it. It extracts into its own folder . In the arduino IDE (Integrated Development Environment) open the folder then the "Phant_EthernetwithPressure_temp.ino" file and all the others should be there as tabs in the IDE. Expand your page sideways if you don't see them all
You will have to go through the code to adjust the private and public keys to those you are given by https://data.sparkfun.com/ when you set up your personal data site. You will also have to change the Mac address to one from your Ethernet device. If your sensors are different you may have to mess about a bit to get the readings properly. Your modem may be different , mine is a Netgear DGN1000 wireless router.The required addresses may be different but mine sets up on 192.168.0.0 through to .256 or so so I chose 192.168.0.178 and used that . You can use whatever you want.
Recent Arduino IDE's seem to have all the libraries needed but you may have to download those and install them in your libraries folder for this to compile. SPI, DHT Ethernet are all needed so if it does not immediately compile on download look in the libraries folder of the Arduino installation and check in the import menu of the IDE to see if DHT or whatever is available . If not Google the library say "Arduino DHT library download" and follow the prompts and install notes. If you don't have all the libraries installed it won't compile.
Check back for comments and updates I will make accordingly .
Ignore the green wire above it was used to trigger a send whenever I wanted to test the setup. The code is left with lots of tests still in for debugging . If anyone is good with interupts there could be a saving of power by powering down between pushes to the server. Please post your code in the comments if you do so.
I'm working on putting this on the ESP8266 ESP12 board now which gets rid of the Arduino $30 and Ethernet shield $12 and uses ESP8266 instead $4. Data going up now but trouble with BMP180 atm