I would not make a top pair bluff at stakes 100 NL and below. There are too many people that play passively and wait for you to bet with their low pocket pairs or low pairs. A hand I had recently at 200 (!) NL illustrates this:

***** Hand History for Game 2249807971 *****
$200 NL Hold'em - Thursday, June 23, 02:38:17 EDT 2005
Table Table 36543 (Real Money)
Seat 2 is the button
Total number of players : 10
Seat 1: hoganAA ( $137.8 )
Seat 2: moon_li ( $113.3 )
Seat 3: SunDevil87 ( $277 )
Seat 4: elselselsels ( $228.6 )
Seat 5: mark_beenyc ( $190.7 )
Seat 6: Cole333 ( $205.05 )
Seat 7: Wooody68 ( $100.82 )
Seat 9: Kingfish__ ( $197 )
Seat 10: bigdogskis ( $312.15 )
Seat 8: poseidon68 ( $112.12 )
SunDevil87 posts small blind [$1].
elselselsels posts big blind [$2].
** Dealing down cards **
Dealt to Kingfish__ [ Ah Kh ]
>You have options at Table 41397 Table!.
mark_beenyc folds.
Cole333 folds.
Wooody68 calls [$2].
poseidon68 folds.
>You have options at Table 49238 Table!.
Kingfish__ raises [$7].
bigdogskis folds.
hoganAA folds.
moon_li folds.
SunDevil87 folds.
elselselsels folds.
Wooody68 calls [$5].
** Dealing Flop ** [ 5h, 4s, 7d ]
Wooody68 checks.
>You have options at Table 41397 Table!.
Kingfish__ checks.
** Dealing Turn ** [ Kc ]
Wooody68 checks.
Kingfish__ bets [$10].
Wooody68 calls [$10].
** Dealing River ** [ 9d ]
Wooody68 checks.
Kingfish__ bets [$20].
Wooody68 calls [$20].
Kingfish__ shows [ Ah, Kh ] a pair of kings.
Wooody68 doesn't show [ Td, Tc ] a pair of tens.
Kingfish__ wins $74 from the main pot with a pair of kings.