So far we've visited the Kazanskiy Sobor (Kazan Cathedral) which is nice. It is still functioning as a church today, where many cathedrals are museums nowadays. This means that the church is very solemn. The problem I personally have with it is that the exterior is a rather shameless attempt to copy the San Pietro in Rome. Inevitably the best details about that one are lost in the design. The builders intended to built it using materials only from Russia itself, which is why the granite and the marble have a very peculiar color, unlike most you'll ever see. The reason they built it was to honor the general who defeated Napoleon. For this he was declared a saint by the clergy, and his mortal remains are on display there, together with an icon which are both much revered by the local population. Because it is still functioning it has a large collection of ancient icons, all of which are revered. Every believer who passes them crosses him/herself, lights a candle and kisses the display. And every once in a while a babuschka (= old crone) will come by and clean the display minutely and thoroughly (after crossing herself once more of course).

And then we did the Cathedral of The Saviour On The Blood. "The Blood" is the blood of Czar Alexander II, which was fatally shot at that very spot in 1881. Contrary to the neo-classical Kazanskiy Sobor and much of the churches in St. Petersburg, the church is designed as classic Russian-Orthodox. What gives away that it isn't, is the fact that the entire interior is one volume. The entire surface of the inside and parts of the outside (together some 7000 m2 I'm told) are covered in mosaics. Breathtaking and painstaking! It took more than 27 years to restore the church to it's former glory after the communists used it as a storage house for several decades.

Also we visited the Wodka museum, which was nice too. The clever people there have set up an exposition of just 2 halls, after which you end up in a 17th century style Traktir (wodka/eating cafe), with a huge collection of wodkas. Although none of us rarely do it, we just HAD to take a picture of JV standing by those. JV and I made it a quest to drink a bottle of a different brand of wodka each day, and so far, we're doing pretty well (good wodka costs around 100 RUR here, which is about 3 EUR).
We saw the military historical museum (JV's comment: "Hotel security". Mine: "ToysToysToys!"), but we decided not to go in. It used to be the armoury, but now they have a great collection of artillery from 1600-WWII and other weaponry from WWII (such as Stalin's Organs, loaded Missile Trucks, tanks, Extremely heavy artillery and so on).
And of course The Convent, with a huge graveyard with celebrities buried such as Shostakovich. It's pretty strange to see how communism influenced graves. Russians' most common way to bury people was using these small obelisque stones with a little bath-shaped flower bed before them and (if you were lucky) a fence around it. Of course this principal design elaborates when more money is involved, including the standard crosses & stuff. People here are most probably buried vertically though, because the diameter of the graves remains to small for any human to lie in. Communism, however, changed all of this of course with it's highly atheistic anti-church attitude. Suddenly, the little obelisks aren't mounted with a cross anymore, but with a red star. While the Christians use white round obelisks, the Soviets clearly preferred a darker, cornered variety, with the star in very bright red. Where famous people are involved, they start to elaborate by using various kind of granite to make a pedestal and a sort of open vault, with golden letters and the CCCP's crest on it. Also they did something I hadn't seen before: they made small-scale "serial graves". We saw several graves "to the people who tragically perished during the accident at this-and-that plant" or something of the sort. I don't know if these people (usually from 5 up to 30 at a time) are buried separately elsewhere, but my guess would be they weren't. 
Darn... 3 min. of internet time left. I'm gone.