Singed is my favourite toplaner.
Mostly because of his interrupting potential.

Health 2011 at 18 (429 + 93.06/level)
Mana 1025 at 18 (260 + 45/level)
Speed 320
Armor 93.6 at 18 (22.2 + 4.2/level)
Magic Resist 35
Critical Chance 6.25% at 18 (2% + 0.25%/level)
Health Per 5 Sec 17 at 18 (7.65 + 0.55/level)
Mana Per 5 Sec 10.4 at 18 (4.45 + 0.35/level)
Range 100

Pro's
High damage over time.
Great tank.
Great initiate with fling.
One of the best slows in game.
Great farmer.
Good damage at lvl 6 from ult
Can easily farm in between towers
Con's
Low mana early game.
Easily kited.
Hard to farm without pushing.
Can't jungle well.

Singed descended from a long line of Zaun's revered chemists. Even in his youth, his talent for concocting potions far outstripped that of his peers, and he quickly distinguished himself from his less extraordinary chemist compatriots. It came as no surprise to anyone when he was selected for apprenticeship by the infamous Warwick, master apothecary on a lucrative retainer with the Noxian military during their campaign against Ionia. Within Warwick's laboratories, Singed toiled without end, rapidly absorbing every detail of his predecessor's deadly craft. Singed had little concern for the death and destruction that was the fruit of his labors. By the time the curse of lycanthropy descended to claim his master, Singed was poised and eager to make the transition from workhorse to innovator; he was ready to share his genius by bringing a new brand of suffering to the Ionian front. His zeal for progress was unquenchable, and when suitable test subjects proved to be in short supply, the eager chemist was often thought to turn his volatile mixtures on his own flesh.

When the uneasy peace created by the League of Legends settled on the world, Singed journeyed to the one place where he was still able to showcase his beloved craft: the Institute of War. By this time he was barely even a man, his body both ruined and sustained by his ingenious craft. A thousand burns - accidents of shadow and flame - mar his ravaged form, and exposure to such harsh conditions has deadened his nerves, hardened his body, and strengthened his physique, transforming him into a veritable juggernaut. This, combined with a formidable arsenal of deadly concoctions, makes Singed a force to be reckoned with on the Fields of Justice.

"My deadliest dose shall bear my patron's name!" - Singed, having just christened the Insanity Potion

Empowered Bulwark (passive)
Increases Singed's health by .25 for each mana point he has.

Poison Trail
Toggle: Singed lays a poisonous trail which lasts for 3.25 seconds and deals 22 / 34 / 46 / 58 / 70 (+30% of ability power) magic damage per second to enemies for 3 seconds.

Mega Adhesive
Singed throws a vial of mega adhesive on the ground causing all enemies who touch it to be slowed by 35 / 45 / 55 / 65 / 75% for as long as they are in the adhesive and for 1 second once they are out of it.

Fling
Singed flings an enemy over his shoulder (500 units), dealing 100 / 150 / 200 / 250 / 300 (+100% of ability power) magic damage.

Insanity Potion
Singed drinks a potent brew of chemicals, granting him 10 / 15 / 20% crowd control reduction and 35 / 50 / 65 ability power, armor, magic resistance, movement speed, health regeneration per 5, and mana regeneration per 5 for 25 seconds.

Ninja Tabi: Good, low cost boots vs ad champs. Helps vs long range opponents
My primary choice because most junglers are ad too.

Mercury's Treads: Magic resist is always good. Tenancy to reduce cc when interrupting enemy team. Gives you better escape chance

Sorcerers Boots: Bit of a troll item, your opponent wouldn't know what hit him.
Magic pen works good when being chased through poison

Boots of swiftness: Good, not the best to my opinion. You are harder to catch up on but it gives no armor nor damage
Thornmail: As I said, a very good item. I have used this before to change the game, when there was an AD too strong, and it is very cheap, so, don't hesitate when buy it. You can buy it instead of your second Warmog's Armor

Frozen Heart: Great item to help your team with because of the passive, Mana and 99 armor.

Abyssal Scepter: Great item because of passive and ap. Although the passive range is shorter than the range of your poison, still a good choice.

Rod Of Ages: Best item in my opinion, You might even want to consider buying two. You get a great health bonus because of your passive.

Aegis of the legion: Good item but i prefer to get more damage. Will work if your team is struggling.

Rylai's Sceptre: A good item, It gives your poison a slow and makes it harder for your opponents to chase you, ZAGood health and ap too.

Haunting guise: Magic pen for a nasty suprise but isn't that effective late game.

Hextech Revolver: Key item in my build, spellvamp is really great when a whole team is chasing you, Also makes it easier to take golems or wolves.

Ghost: Undaubtly the best spell for singed.

Teleport: good for a little map pressure, Teleport to bot for a 5v2 and the game turns in your favour

Ignite: Good for 1v1 suprise damage.

Flash: bit of an overkill if you ask me, bt it might save your life 1 or 2 times.

Heal: good, nothing further.

Exhaust: Decent, but your opponent will stop chasing you.

http://www.leaguereplays.com/summoners/EUW/LolWutBigJ/
some of my lesser work as singed on ranked.
Play Video Play Video

Teemo:8/10 Hard early game. Ask for a few ganks and dont miss too much farm. lategame you will be able to beat him.

Jayce:7/10 Dodge as much as possible. Try to fling him before he can land hammer E

Jax: 3/10 Ask your jungler not to gank. you are able to win without his help. Don't fling him, he will just jump back, instead save the mana for poison.

Zed: 3/10 You have more sustain late game. be carefull for his lvl 6 burst.

Fiora 4/10 Concentrate on your farm.

Irelia 5/10 Get hp before armor. And farm while harrasing her.