Well, the noise reduction is a no brainer, the boss NS-2 (around $75) is the classic noise supressor that a lot of people use, including Yngwie, who uses 2 in his chain. Another great one is the Rocktron HUSH (around $50-75) pedal. For years, pro's have been using the hush in there racks, and reciently rocktron came out with the pedal version, which is great, and so simple a caveman could use it (one knob, one switch, dur)..The difference between the two is that the NS-2 is a lot more tweakable.
Now with OD pedals and Wah's, you have a lot more options open to you, and this is where it gets tricky. You need to find something that sounds good to you, so you really need to try out tons of pedals at your local music store. If you don't want to do this, you could get, as a few people already mentioned, the all-in-one units like the ME-6 and Line6 POD XT live are great places to start.
However, all of this is all well and good, but if you dont have a good amp to begin with, it isnt going to make your sound any better,infact you may end up sounding worse then when you started. What amp are you using right now?
I currently have 5 OD pedals in my collection: DOD YJM308, Marshall DriveMaster, Ibanez TS-808RI, Danelectro Daddy-o and a Boss SD-1.
The first one, the DOD YJM 308 is my favorite and the one I have used the most. This pedal adds a lot of punch and harmonics to your guitar output, without coloring it to much. A bit noisy at higher gain settings, which is why Yngwie runs 2 NS-2's after it. Great OD pedal for only $40.
I also have a Marshall Drivemaster which was my first OD pedal. It has a similar tone to the 308, but a bit more defined and crunchy due to the 3 band EQ. A fairly rare pedal nowadays, glad I kept it. they go for around $80-100 depending on condition.
Ibanez have made some great pedals over the years, including what is known to be the "Holy Grail" of OD pedals, the TS-808, of which I have the reissue. So far, I really like it, its a bit more transparent than the 308 with a little less bottom end and smother gain, and fairly quiet. Quite expensive though at $160, but cheaper than the origional 808's which have been going for $400+.
The Daddy-O and SD-1 are fairly similar in tone. The SD-1 is closer to the 808 and 308, and the daddy-o is more torwards the Drivemaster, however, these 2 pedals have a more brown tone to them. I dont use them much. The plus side to them is that there both cheap. ($40ish)
Wah pedals are another pain in the butt. Morley and Dunlop probably make the best. Dunlop crybabys are the set standard when it comes to wah. They tend to be very vocal and harsh with a wide EQ sweep. They all have the nose down button, which I personally dont care for anymore.
Morley wahs are a totally different animal. There wahs tend to have more subtle tone with less coloring and less sweep. There wahs feature one of the greatest innovations of any wah pedals, the switchless optical sensors which are found in the Bad Horsie 1 and 2. Earlier wah's had an external stomp switch, but are still optical.
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