Please go take a look at sga_guide, and the master list (you will have to join to see a number of the posts). I hope you'll be inspired to sign up to write a guide!
There are a number of characters and pairings that still need guides written for them. SG1 people, there's room for pairings that are crossovers with SGA. I know at least someone is writing a Vala Mal Doran/John Sheppard guide. ETA: SGA/SGU crossovers are welcome as well, of course!