You have to look at realistic options in FA. None of the big-time receivers (Austin, Marshall, Jackson) will ever see the open market. Mostly because their teams would franchise them, but also because without a new CBA, they don't become unrestricted.
If you look at potential options, here's what you have.
WR-Antonio Bryant, Malcom Floyd, Kevin Walter, not much else to choose from.
TE-Tony Scheffler, Ben Watson, Bo Scaife, maybe Owen Daniels as the Texans have several other key FA's to focus on (Dunta Robinson, DeMeco Ryans).
NT-Justin Bannan, Aubreyo Franklin (likely franchised), Ryan Pickett (could be available as Packers have Raji in the wings).
ILB-Tim Dobbins, Karlos Dansby (could be franchised), Ryans (likely a pipedream, but you never know), Derrick Johnson, Kirk Morrison (not sure how he'd translate to a 3-4).
OLB-Shawne Merriman (very expensive), Thomas Howard (again, not a typical 3-4 backer), Aaron Kampman (didn't make smooth transition to 3-4 backer)
FS- Not many options, although if Darren Sharper could play anywhere near to what he did this season, he would be a nice option.
I personally,would go for Bryant, Bannan and break the bank for Dansby if he became available. Dobbins might be a nice fallback option.