I have included some of my favourite websites and blogs below. Most are related to SE Asia / China in some way or another and I've tried to organize them by country where appropriate.

Lao Bumpkin
This is probably THE blog about all things Lao. A must read.
Lao Miao
A very close second but has a wealth of practical travel information (including bus timetables!) 
Travels with a Nine Year Old
An excellent site about a single mother and child (now 11) traveling through SE Asia.
Legal Nomads
Probably the first blog I ever bookmarked and a good example of how traveling and writing can help you forge a new career path (formerly a lawyer). Very polished site and cute girl too.
Interesting and insightful blog by a health worker in Yunnan Province, China. A post about fake Apple stores in Kunming exploded across the web.

Travel Sites

The number one travel site for most of South East Asia including comprehensive coverage of Thailand, Laos, Cambodia and Vietnam. The Indonesia section is expanding while Malaysia coverage remains limited. Anything you can't find on the site will be answered on the forum without a doubt 

Boat Landing Guesthouse & Restaurants
To my knowledge, one of the first eco-lodges in Northern Laos. Includes lots of information on Luang Nam Tha town and region.
Excellent online maps of Thailand and Laos. Hard copies can be purchased in country.
Phongsali Province Tourism website
Basic website with map and trekking information
Bolevan Plateau Website
A Southern Laos loop (big or small) often done by motorbike but some can be done via bus (not been updated for a while).
Muang Long Tourism Office
Another fairly basic website but with trekking and area information as well as contact details.