I get my weed from a "legal" medical marijuana supplier in San Francisco. The guy always has at least 5 or 6 strains, plus hash, brownies, etc. The best thing is that I can trust that when I buy "white widow", "blueberry" etc it is what he says it is.

Anyhow, some of the ones I can remember are

Purple Erkle- Seriously potent 100% indica. I've smoked for 25 years and this is by far the strongest stuff I've ever come across. That's purple erkle in the pic I attached.
Manatuska Thunderfuck-Another seriously stong strain
Green Erkle- a purple erkle crossed with some other indica. Good shit but doesn't compare to the purple
Sour Deisel-lives up to it's reputation
Jack Herer-One of my favorites. A really potent sativa
White Widow- a good smoke but my personal opinion is that it's overrated
Purple Kush- Pretty decent indica. Nothing special though. An example of "just because it's purple doesn't mean it's great"
"Premium Humboldt Outdoor"- Not sure of the exact strain but definitely 100% (or nearly so) sativa. Really nice up and happy high.
Green Dragon- A strain, not the alcohol/bud concoction. Nice indica/sativa mix
Black Domina- 100% indica. Can you say "couch lock"?
Silver Haze
Blueberry
Durban Poison
Juicy Fruit
Mango
Pot O' Gold

Others that I forgot