Everyone and their plumber forming independent expenditure committees

Everyone wants in on the unlimited fun in this post-Citizens United world. Even Joe the Plumber—legally known as Samuel Joseph Worzelbacher—has formed an independent expenditure only committee.
Now, in addition to Joe and several other new IE committee registrants, a Political Action Committee, unconnected to any candidate, has asked the Federal Election Commission to determine it legal for groups like theirs to receive unlimited contributions to pay for independent expenditures such as political ads, which expands on what the FEC made clear in two advisory opinions in mid-July.
The group that submitted the request, the National Defense PAC, supports and contributes to veterans running for office who agree with their views. NDPAC plans to store the individual contributions in a separate bank account and only use those funds for independent expenditures—generally electioneering communications that are not coordinated with a candidate. 
The difference between the newly-formed Independent expenditure committees, like Florida is Not For Sale or Joe the Plumber's committee, and groups like NDPAC can be subtle and hard to understand. An aspect of IE committees (or IE-only PACs) is they are non-connected political commitees as is NDPAC, but NDPAC does not solely make independent expenditures. The Advisory Opinion Request submitted by the PAC explains those subtlties in the way the two raise funds and spend those funds: 
"A non-connected political committee has two choices with virtually identical reporting obligations. It may operate as an IE-only PAC and raise and expend unlimited funds from any corporation, union, or individual for lE's only. Or, it may operate as a non-IE-only PAC, raise and expend amount-limited contributions from individuals and other political committees only, and make amount-limited direct contributions to candidates as well as unlimited expenditures for LE's. Either approach requires the same accounting of receipts, sources, and expenditures."