Wolverine was created in the Weapon X program (in fact he became Weapon X). Does this mean there were nine other attempts at bonding adamantium to a skeleton, or does it mean there were 9 other separate projects designed at making a weapon?
The Weapons Plus program deals with various experiments - mostly genetic in nature. While adamantium has figured into some of the experiments, it is not a primary component.
Comic Continuity (Primarily Earth-616, but some projects from alternate futures have time traveled and become involved with the main timeline)
Weapon 0: The precursor to Project Rebirth. Began as a collaborative effort between US, British and German scientists. The project splintered once WW2 began. No details have been revealed regarding exact test subjects or results. Dr. Josef Reinstein defected to the US and took the name Dr. Abraham Erskine.
Weapon I: (AKA: Project Rebirth) - Resulted in the creation of Captain America, Isaiah Bradley, and Protocide as well as a number of failed experiments. Captain America's original shield was made of an adamantium steel-vibranium alloy. Dr. Erskine was one of the primary scientists involved.
Weapon II: Genetic experimentation on various animals, such as this squirrel which did appear to have an adamantium skeleton and claws, as well as an enhanced healing factor.
Weapon III: Experimentation on Skinless Man, a mutant with elastic skin.
Weapon IV: More experimentation on animals.
Weapons V & VI: Experimentation on various ethnic minorities.
Weapon VII: (AKA: Project Homegrown) Experimentation on soldiers in Vietnam. Attempts made at adamantium bonding. Nuke was the only known success of Project Homegrown, but Cyber may have been one of the subjects to undergo adamantium bonding tests. The UK had its own version of Project: Homegrown called The Black Budget. Both it and The Mercy Corporation (an offshoot of SHIELD) were successful at creating their own super-soldiers.
Weapon VIII & IX: Experimentation on criminals and psychopaths.
Weapon X: Experimentation on mutants. Wolverine, Sabretooth and Deadpool are the most notable subjects. Adamantium bonding was experimented with, but was not the sole focus of the experiments. Once dissolved, Weapon X became Department K in Canada.
Weapon XI: Unknown, however Rob Liefeld has made comments implying that Garrison Kane was intended to be Weapon XI. Kane would later become part of the Weapon X program thanks to time travel and even uses the name "Weapon X".
Weapon XII: Experimentation creating an AI with nanosentinel technology to be part of the Super-Sentinels. Resulted in the creation of Huntsman.
Weapon XIII: Further experimentation with nanosentinel technology, resulting in the creation of Fantomex.
Weapon XIV: Experimentation on the Stepford Cuckoos, a set of quintuplets with telepathic powers.
Weapon XV: Experimentation to create a high powered super-sentinel. Resulted in the creation of Ultimaton.
Weapon XVI: Resulted in creation of a super-powered virus known as "Allgod", which enslaves anyone it infects.
Weapon Infinity: (AKA Project Deathlok) - Experimentation in reanimation of corpses of soldiers and superheroes. Resulted in the creation of an army of reanimated soldiers.
The Facility: Not technically part of the "Weapons Plus" programs, The Facility was an unaffiliated program aiming to recreate the results of the Weapon X program. In specific, they were attempting to bond adamantium to skeletons. When all of their attempts failed, they turned to genetic cloning, resulting in Laura Kinney (X-23).
Fox/X-Men Movie Continuity (Earth-10005)
Note that this is sort of a giant cluster#### and makes very little sense.
Weapon Null/0: This project exists only in a novel based off of X-Men Origins: Wolverine, and should be considered non-canon. An early super-soldier program focused on bioenhancing soldiers to turn them into self-contained organic weapons. The project was shelved due to excessive costs. Four resulting soldiers were mentioned: Slammer, Blowtorch, Cypher, and Bipolar.
Weapon XI: Strangely, prior to the timeline alterations of X-Men: Days of Future Past, Deadpool was referred to as "Weapon XI". Whether or not the Weapon XI was actually just a branch, side project or a whole new project separate from Weapon X has never been clearly defined.
No other details regarding other "Weapons" programs have been revealed in this continuity.
Marvel Cinematic Universe (Earth-19999)
Project Rebirth: A cinematic counterpart to Weapon 1 of the Earth-616 universe, but no "Weapon" designation is ever mentioned. It was largely spearheaded by Dr. Abraham Erskine.
Weapon Plus: No details have been revealed about exactly who, or what this program experimented on, but the super-soldier serum injected into Emil Blonsky is labeled as being developed by "Dr. Reinstein", an alias of Dr. Abraham Erskine in Earth-616. It should be noted that while multiple wiki sites list Reinstein as an alias of Erskine in this continuity, no direct connection has been made in any movie or supplemental material; The connection is being largely assumed based on the Earth-616 facts.